Pacific War
The Pacific War, sometimes called the Asia-Pacific War,Williamson Murray, Allan R. Millett A War to be Won: Fighting the Second World War, Harvard University Press, 2001, p. 143 was the theater of World War II that was fought in the Pacific and East Asia. It was fought over a vast area that included the Pacific Ocean and islands, the South West Pacific, South-East Asia, and in China (including the 1945 Soviet–Japanese conflict).

The Second Sino-Japanese War between the Empire of Japan and the Republic of China had been in progress since 7 July 1937, with hostilities dating back as far as 19 September 1931 with the Japanese invasion of Manchuria.Roy M. MacLeod, Science and the Pacific War: Science and Survival in the Pacific, 1939–1945, Kluwer Academic Publishing, p. 1, 1999 However, it is more widely acceptedYouli Sun, China and the Origins of the Pacific War, 1931–41, Palgrave MacMillan, p. 11 that the Pacific War itself began on 7/8 December 1941, when Japan invaded Thailand and attacked the British possessions of Malaya, Singapore, and Hong Kong as well as the United States military bases in Hawaii, Wake Island, Guam and the Philippines.John Costello, The Pacific War: 1941–1945, Harper Perennial, 1982Japan Economic Foundation, Journal of Japanese Trade & Industry, Volume 16, 1997

The Pacific War saw the Allied powers pitted against the Empire of Japan, the latter briefly aided by Thailand and to a much lesser extent by its Axis allies, Germany and Italy. The war culminated in the atomic bombings of Hiroshima and Nagasaki, and other large aerial bomb attacks by the United States Army Air Forces, accompanied by the Soviet invasion of Manchuria on 8 August 1945, resulting in the Japanese announcement of intent to surrender on 15 August 1945. The formal and official surrender of Japan took place aboard the battleship  in Tokyo Bay on 2 September 1945. Following its defeat, Japan's Shinto Emperor stepped down as the divine leader through the Shinto Directive, because the Allied Powers believed this was the major political cause of Japan's military aggression and deconstruction soon took place to install a new liberal-democratic constitution to the Japanese public as the current Constitution of Japan.

Overview

Names for the war
thumb|left|upright|Generalissimo Chiang Kai-shek, Allied Commander-in-Chief in the China theatre from 1942 to 1945.
In Allied countries during the war, "The Pacific War" was not usually distinguished from World War II in general, or was known simply as the War against Japan. In the United States, the term Pacific Theater was widely used, although this was a misnomer in relation to the British campaign in Burma, the war in China and other activities within the Southeast Asian Theater.

Japan used the name , as chosen by a cabinet decision on 10 December 1941, to refer to both the war with the Western Allies and the ongoing war in China. This name was released to the public on 12 December, with an explanation that it involved Asian nations achieving their independence from the Western powers through armed forces of the Greater East Asia Co-Prosperity Sphere. Japanese officials integrated what they called the  into the Greater East Asia War.

During the American military occupation of Japan (1945–52), these Japanese terms were prohibited in official documents, although their informal usage continued, and the war became officially known as . In Japan, the  is also used, referring to the period from the Mukden Incident of 1931 through 1945.

Participants
thumb|400px|right|Political Map of the Asia-Pacific Region, 1939.
thumb|upright|Generalissimo Chiang Kai-shek and General Joseph Stilwell, Allied Commander-in-Chief in the China theatre from 1942–1945.
The Axis states which assisted Japan included the authoritarian government of Thailand in World War II, which quickly formed a temporary alliance with the Japanese in 1941, as the Japanese forces were already invading the peninsula of southern Thailand. The Phayap Army sent troops to invade and occupy northeastern Burma, which was former Thai territory that had been annexed by Britain much earlier. Also involved were the Japanese puppet states of Manchukuo and Mengjiang (consisting of most of Manchuria and parts of Inner Mongolia respectively), and the collaborationist Wang Jingwei regime (which controlled the coastal regions of China).

The official policy of the U.S. Government is that Thailand was not an ally of the Axis, and that the United States was not at war with Thailand. The policy of the U.S. Government ever since 1945 has been to treat Thailand not as a former enemy, but rather as a country which had been forced into certain actions by Japanese blackmail, before being occupied by Japanese troops. Thailand has been treated by the United States in the same way as such other Axis-occupied countries as Belgium, Czechoslovakia, Denmark, Greece, Norway, Poland, and the Netherlands.

Japan conscripted many soldiers from its colonies of Korea and Formosa (Taiwan). To a small extent, some Vichy French, Indian National Army, and Burmese National Army forces were active in the area of the Pacific War. Collaborationist units from Hong Kong (reformed ex-colonial police), Philippines, Dutch East Indies (the PETA) and Dutch Guinea, British Malaya and British Borneo, Inner Mongolia and former French Indochina (after the overthrow of Vichy French regime) as well as Timorese militia also assisted Japanese war efforts.

Germany and Italy both had limited involvement in the Pacific War. The German and the Italian navies operated submarines and raiding ships in the Indian and Pacific Oceans. The Italians had access to "concession territory" naval bases in China, while the Germans did not. After Japan's attack on Pearl Harbor and the subsequent declarations of war, both navies had access to Japanese naval facilities.

The major Allied participants were the United States, the Republic of China, the United Kingdom (including the armed forces of British India, the Fiji Islands, Samoa, etc.), Australia, the Commonwealth of the Philippines, the Netherlands (as the possessor of the Dutch East Indies and the western part of New Guinea), New Zealand, and Canada, all of whom were members of the Pacific War Council. Mexico, Free France and many other countries also took part, especially forces from other British colonies.

The Soviet Union fought two short, undeclared border conflicts with Japan in 1938 and 1939, then remained neutral until August 1945, when it joined the Allies and invaded the territory of Manchukuo, Republic of China, Inner Mongolia, the Japanese protectorate of Korea and Japanese-claimed islands such as Sakhalin coordinated notably between the Red Banner Pacific Fleet and the US Navy's Task Force 38.

Theaters
thumb|The Pacific War Council as photographed on 12 October 1942. Pictured are representatives from the United States (seated) China, the United Kingdom, Australia, Canada, the Netherlands, New Zealand, and the Philippine Commonwealth.
Between 1942 and 1945, there were four main areas of conflict in the Pacific War: China, the Central Pacific, South East Asia and the South West Pacific. U.S. sources refer to two theaters within the Pacific War: the Pacific theater and the China Burma India Theater (CBI). However these were not operational commands.

In the Pacific, the Allies divided operational control of their forces between two supreme commands, known as Pacific Ocean Areas and Southwest Pacific Area. In 1945, for a brief period just before the Japanese surrender, the Soviet Union and its Mongolian ally engaged Japanese forces in Manchuria and northeast China.

Historical background

Conflict between China and Japan

thumb|170px|Chinese casualties of a mass panic during a June 1941 Japanese aerial bombing of Chongqing.
By 1937, Japan controlled Manchuria and was ready to move deeper into China. The Marco Polo Bridge Incident on 7 July 1937 provoked full-scale war between China and Japan. The Nationalist and Communist Chinese suspended their civil war to form a nominal alliance against Japan, and the Soviet Union quickly lent support by providing large amount of materiel to Chinese troops. In August 1937, Generalissimo Chiang Kai-shek deployed his best army to fight about 300,000 Japanese troops in Shanghai, but, after three months of fighting, Shanghai fell. The Japanese continued to push the Chinese forces back, capturing the capital Nanking in December 1937 and committed which was known as Nanking Massacre. In March 1938, Nationalist forces won their first victory at Taierzhuang. but then the city of Xuzhou was taken by Japanese in May. In June 1938, Japan deployed about 350,000 troops to invade Wuhan and captured it in October. The Japanese achieved major military victories, but world opinion—in particular in the United States—condemned Japan, especially after the Panay incident.

In 1939, Japanese forces tried to push into the Soviet Far East from Manchuria. They were soundly defeated in the Battle of Khalkhin Gol by a mixed Soviet and Mongolian force led by Georgy Zhukov. This stopped Japanese expansion to the north, and Soviet aid to China ended as a result of the signing of the Soviet–Japanese Neutrality Pact at the beginning of its war against Nazi Germany.Edward J. Drea, Nomonhan: Japanese-Soviet Tactical Combat, 1939 (2005)

In September 1940, Japan decided to cut China's only land line to the outside world by seizing Indochina, which was controlled at the time by Vichy France. Japanese forces broke their agreement with the Vichy administration and fighting broke out, ending in a Japanese victory. On 27 September Japan signed a military alliance with Germany and Italy, becoming one of the three Axis Powers. In practice, there was little coordination between Japan and Germany until 1944, by which time the U.S. was deciphering their secret diplomatic correspondence.Boyd, Carl. Hitler's Japanese confidant: General Ōshima Hiroshi and MAGIC intelligence, 1941–1945 (1993)

The war entered a new phase with the unprecedented defeat of the Japanese at Battle of Suixian–Zaoyang and 1st Battle of Changsha. After these victories, Chinese nationalist forces launched a large-scale counter-offensive in early 1940; however, due to its low military-industrial capacity, it was repulsed by Japanese army in late March 1940. In August 1940, Chinese communists launched an offensive in Central China; in retaliation, Japan instituted the "Three Alls Policy" ("Kill all, Burn all, Loot all") in occupied areas to reduce human and material resources for the communists.Chinese-Soviet Relations, 1937–1945; Garver, John W.; p. 120. By 1941 the conflict had become a stalemate. Although Japan had occupied much of northern, central, and coastal China, the Nationalist Government had retreated to the interior with a provisional capital set up at Chungking while the Chinese communists remained in control of base areas in Shaanxi. In addition, Japanese control of northern and central China was somewhat tenuous, in that Japan was usually able to control railroads and the major cities ("points and lines"), but did not have a major military or administrative presence in the vast Chinese countryside. The Japanese found its aggression against the retreating and regrouping Chinese army was stalled by the mountainous terrain in southwestern China while the Communists organised widespread guerrilla and saboteur activities in northern and eastern China behind the Japanese front line.

Japan sponsored several puppet governments, one of which was headed by Wang Jingwei. However, its policies of brutality toward the Chinese population, of not yielding any real power to these regimes, and of supporting several rival governments failed to make any of them a viable alternative to the Nationalist government led by Chiang Kai-shek. Conflicts between Chinese communist and nationalist forces vying for territory control behind enemy lines culminated in a major armed clash in January 1941, effectively ending their co-operation.

Japanese strategic bombing efforts mostly targeted large Chinese cities such as Shanghai, Wuhan, and Chongqing, with around 5,000 raids from February 1938 to August 1943 in the later case. Japan's strategic bombing campaigns devastated Chinese cities extensively, killing 260,000–350,934 non-combatants.Lind Jennifer M. (2010). "Sorry States: Apologies in International Politics". Cornell University Press, p.28. ISBN 0-8014-7628-3

Tensions between Japan and the West
From as early as 1935 Japanese military strategists had concluded the Dutch East Indies were, because of their oil reserves, of considerable importance to Japan. By 1940 they had expanded this to include Indo-China, Malaya, and the Philippines within their concept of the Greater East Asia Co-Prosperity Sphere. Japanese troop build ups in Hainan, Taiwan, and Haiphong were noted, Japanese Army officers were openly talking about an inevitable war, and Admiral Sankichi Takahashi was reported as saying a showdown with the United States was necessary.

In an effort to discourage Japanese militarism, Western powers including Australia, the United States, Britain, and the Dutch government in exile, which controlled the petroleum-rich Dutch East Indies, stopped selling oil, iron ore, and steel to Japan, denying it the raw materials needed to continue its activities in China and French Indochina. In Japan, the government and nationalists viewed these embargos as acts of aggression; imported oil made up about 80% of domestic consumption, without which Japan's economy, let alone its military, would grind to a halt. The Japanese media, influenced by military propagandists, began to refer to the embargoes as the "ABCD ("American-British-Chinese-Dutch") encirclement" or "ABCD line".

Faced with a choice between economic collapse and withdrawal from its recent conquests (with its attendant loss of face), the Japanese Imperial General Headquarters began planning for a war with the western powers in April or May 1941.

 Japanese preparations 
Japan's key objective during the initial part of the conflict was to seize economic resources in the Dutch East Indies and Malaya which offered Japan a way to escape the effects of the Allied embargo. This was known as the Southern Plan. It was also decided—because of the close relationship between the UK and United States, and the 
Peattie & Evans, KaigunWillmott, Barrier and the Javelin (Annapolis: Naval Institute Press, 1983). belief the US would inevitably become involved—Japan would also require taking the Philippines, Wake and Guam.

Japanese planning was for fighting a limited war where Japan would seize key objectives and then establish a defensive perimeter to defeat Allied counterattacks, which in turn would lead to a negotiated peace.
The attack on the US Pacific Fleet at Pearl Harbor, Hawaii, with carrier-based aircraft of the Combined Fleet was to give the Japanese time to complete a perimeter.
The initial period of the war was divided into two operational phases. The First Operational Phase was further divided into three separate parts in which the major objectives of the Philippines, British Malaya, Borneo, Burma, Rabaul and the Dutch East Indies would be occupied. The Second Operational Phase called for further expansion into the South Pacific by seizing eastern New Guinea, New Britain, Fiji, Samoa, and strategic points in the Australian area. In the Central Pacific, Midway was targeted as were the Aleutian Islands in the North Pacific. Seizure of these key areas would provide defensive depth and deny the Allies staging areas from which to mount a counteroffensive.

By November these plans were essentially complete, and were modified only slightly over the next month. Japanese military planners' expectation of success rested on the United Kingdom and the Soviet Union being unable to effectively respond to a Japanese attack because of the threat posed to each by Germany; the Soviet Union was even seen as unlikely to commence hostilities.

The Japanese leadership was aware that a total military victory in a traditional sense against the USA was impossible; the alternative would be negotiating for peace after their initial victories, which would recognize Japanese hegemony in Asia.Boog et al (2006) "Germany and the Second World War: The Global War", p. 175 In fact, the Imperial GHQ noted, should acceptable negotiations be reached with the Americans, the attacks were to be canceled—even if the order to attack had already been given. The Japanese leadership looked to base the conduct of the war against America on the historical experiences of the successful wars against China (1894–95) and Russia (1904–05), in both of which a strong continental power was defeated by reaching limited military objectives, not by total conquest.

They also planned, should the U.S. transfer its Pacific Fleet to the Philippines, to intercept and attack this fleet en route with the Combined Fleet, in keeping with all Japanese Navy prewar planning and doctrine. If the United States or Britain attacked first, the plans further stipulated the military were to hold their positions and wait for orders from GHQ. The planners noted attacking the Philippines and Malaya still had possibilities of success, even in the worst case of a combined preemptive attack including Soviet forces.

 Japanese offensives, 1941–42 
On 7 December 1941, Japan attacked the American bases in Hawaii. The same day (8 December on the other side of the International Date Line), Japanese forces attacked Guam, Wake Island and the British crown colony of Hong Kong while other Japanese units invaded the Philippines, Thailand and Malaya.

 Attack on Pearl Harbor 
thumb| burned for two days after being hit by a Japanese bomb in the attack on Pearl Harbor.

In the early hours of 7 December (Hawaiian time), Japan launched a major surprise carrier-based air strike on Pearl Harbor without explicit warning, which crippled the U.S. Pacific Fleet, leaving eight American battleships out of action, 188 American aircraft destroyed, and 2,403 American citizens dead. At the time of the attack, the U.S. was not officially at war anywhere in the world as the Japanese embassy failed to decipher and deliver the Japanese ultimatum to the American government before noon December 7 (Washington time), which means that the people killed or property destroyed at Pearl Harbor by the Japanese attack had a non-combatant status. The Japanese had gambled that the United States, when faced with such a sudden and massive blow, would agree to a negotiated settlement and allow Japan free rein in Asia. This gamble did not pay off. American losses were less serious than initially thought: The American aircraft carriers, which would prove to be more important than battleships, were at sea, and vital naval infrastructure (fuel oil tanks, shipyard facilities, and a power station), submarine base, and signals intelligence units were unscathed. Japan's fallback strategy, relying on a war of attrition to make the U.S. come to terms, was beyond the IJN's capabilities.Parillo, Mark P. Japanese Merchant Marine in World War II. (United States Naval Institute Press, 1993).

Before the attack on Pearl Harbor, the 800,000-member America First Committee vehemently opposed any American intervention in the European conflict, even as America sold military aid to Britain and the Soviet Union through the Lend-Lease program. Opposition to war in the U.S. vanished after the attack. On 8 December, the United States, the United Kingdom, Canada, and the Netherlands declared war on Japan, followed by China and Australia the next day. Four days after Pearl Harbor, Nazi Germany and Fascist Italy declared war on the United States, drawing the country into a two-theater war. This is widely agreed to be a grand strategic blunder, as it abrogated the benefit Germany gained by Japan's distraction of the U.S. (predicted months before in a memo by Commander Arthur McCollum) and the reduction in aid to Britain, which both Congress and Hitler had managed to avoid during over a year of mutual provocation, which would otherwise have resulted.

Attacks on Southeast Asia
thumb|right|HMS Prince of Wales (left, front) and HMS Repulse (left, rear) under attack by Japanese aircraft. A destroyer is in the foreground.

British, Australian, and Dutch forces, already drained of personnel and matériel by two years of war with Germany, and heavily committed in the Middle East, North Africa, and elsewhere, were unable to provide much more than token resistance to the battle-hardened Japanese. The Allies suffered many disastrous defeats in the first six months of the war. Two major British warships,  and , were sunk by a Japanese air attack off Malaya on 10 December 1941.

Thailand, with its territory already serving as a springboard for the Malayan campaign, surrendered within 24 hours of the Japanese invasion. The government of Thailand formally allied with Japan on 21 December.

Hong Kong was attacked on 8 December and fell on 25 December 1941, with Canadian forces and the Royal Hong Kong Volunteers playing an important part in the defense. American bases on Guam and Wake Island were lost at around the same time.

Following the Declaration by United Nations (the first official use of the term United Nations) on 1 January 1942, the Allied governments appointed the British General Sir Archibald Wavell to American-British-Dutch-Australian Command (ABDACOM), a supreme command for Allied forces in Southeast Asia. This gave Wavell nominal control of a huge force, albeit thinly spread over an area from Burma to the Philippines to northern Australia. Other areas, including India, Hawaii, and the rest of Australia remained under separate local commands. On 15 January, Wavell moved to Bandung in Java to assume control of ABDACOM.

thumb|left|Japanese battleships ,  and  (more distant)

In January, Japan invaded Burma, the Dutch East Indies, New Guinea, the Solomon Islands and captured Manila, Kuala Lumpur and Rabaul. After being driven out of Malaya, Allied forces in Singapore attempted to resist the Japanese during the Battle of Singapore, but were forced to surrender to the Japanese on 15 February 1942; about 130,000 Indian, British, Australian and Dutch personnel became prisoners of war. The pace of conquest was rapid: Bali and Timor also fell in February. The rapid collapse of Allied resistance left the "ABDA area" split in two. Wavell resigned from ABDACOM on 25 February, handing control of the ABDA Area to local commanders and returning to the post of Commander-in-Chief, India.

thumb|left|The Bombing of Darwin, Australia, 19 February 1942

Meanwhile, Japanese aircraft had all but eliminated Allied air power in Southeast Asia and were making attacks on northern Australia, beginning with a psychologically devastating but militarily insignificant attack on the city of Darwin on 19 February, which killed at least 243 people.

At the Battle of the Java Sea in late-February and early-March, the Imperial Japanese Navy (IJN) inflicted a resounding defeat on the main ABDA naval force, under Admiral Karel Doorman. The Dutch East Indies campaign subsequently ended with the surrender of Allied forces on Java and Sumatra.

In March and April, a powerful IJN carrier force launched a raid into the Indian Ocean. British Royal Navy bases in Ceylon were hit and the aircraft carrier  and other Allied ships were sunk. The attack forced the Royal Navy to withdraw to the western part of the Indian Ocean. This paved the way for a Japanese assault on Burma and India.

thumb|right|200px|Surrender of U.S. forces at Corregidor, Philippines, May 1942

In Burma, the British, under intense pressure, made a fighting retreat from Rangoon to the Indo-Burmese border. This cut the Burma Road, which was the western Allies' supply line to the Chinese Nationalists. In March 1942, the Chinese Expeditionary Force started to attack Japanese forces in northern Burma. On 16 April, 7,000 British soldiers were encircled by the Japanese 33rd Division during the Battle of Yenangyaung and rescued by the Chinese 38th Division, led by Sun Li-jen.. Cooperation between the Chinese Nationalists and the Communists had waned from its zenith at the Battle of Wuhan, and the relationship between the two had gone sour as both attempted to expand their areas of operation in occupied territories. Most of the Nationalist guerrilla areas were eventually taken over by the Communists. On the other hand, some Nationalist units were deployed to blockade the Communists and not the Japanese. Furthermore, many of the forces of the Chinese Nationalists were warlords allied to Chiang Kai-Shek, but not directly under his command. "Of the 1,200,000 troops under Chiang's control, only 650,000 were directly controlled by his generals, and another 550,000 controlled by warlords who claimed loyalty to his government; the strongest force was the Szechuan army of 320,000 men. The defeat of this army would do much to end Chiang's power." The Japanese exploited this lack of unity to press ahead in their offensives.

Filipino and U.S. forces resisted in the Philippines until 8 May 1942, when more than 80,000 soldiers were ordered to surrender. By this time, General Douglas MacArthur, who had been appointed Supreme Allied Commander South West Pacific, had been withdrawn to Australia. The U.S. Navy, under Admiral Chester Nimitz, had responsibility for the rest of the Pacific Ocean. This divided command had unfortunate consequences for the commerce war,Blair, Silent Victory and consequently, the war itself.

Threat to Australia
In late 1941, as the Japanese struck at Pearl Harbor, most of Australia's best forces were committed to the fight against Hitler in the Mediterranean Theatre. Australia was ill-prepared for an attack, lacking armaments, modern fighter aircraft, heavy bombers, and aircraft carriers. While still calling for reinforcements from Churchill, the Australian Prime Minister John Curtin called for American support with a historic announcement on 27 December 1941:Cited in Frank Crowley (1973) Vol 2, p.51

thumb|left|Dutch and Australian PoWs at Tarsau, in Thailand in 1943. 22,000 Australians were captured by the Japanese; 8,000 died as prisoners of war.

Australia had been shocked by the speedy collapse of British Malaya and Fall of Singapore in which around 15,000 Australian soldiers became prisoners of war.  Curtin predicted that the "battle for Australia" would now follow. The Japanese established a major base in the Australian Territory of New Guinea in early 1942. On 19 February, Darwin suffered a devastating air raid, the first time the Australian mainland had been attacked. Over the following 19 months, Australia was attacked from the air almost 100 times.

right|thumb|U.S. General Douglas MacArthur, Commander of Allied forces in the South-West Pacific Area, with Australian Prime Minister John Curtin 
Two battle-hardened Australian divisions were steaming from the Mid-East for Singapore. Churchill wanted them diverted to Burma, but Curtin insisted on a return to Australia. In early 1942 elements of the Imperial Japanese Navy proposed an invasion of Australia. The Japanese Army opposed the plan and it was rejected in favour of a policy of isolating Australia from the United States via blockade by advancing through the South Pacific. The Japanese decided upon a seaborne invasion of Port Moresby, capital of the Australian Territory of Papua which would put Northern Australia within range of Japanese bomber aircraft.

President Franklin Roosevelt ordered General Douglas MacArthur in the Philippines to formulate a Pacific defence plan with Australia in March 1942. Curtin agreed to place Australian forces under the command of MacArthur who became Supreme Commander, South West Pacific. MacArthur moved his headquarters to Melbourne in March 1942 and American troops began massing in Australia. Enemy naval activity reached Sydney in late May 1942, when Japanese midget submarines launched a daring raid on Sydney Harbour. On 8 June 1942, two Japanese submarines briefly shelled Sydney's eastern suburbs and the city of Newcastle.

Allies re-group, 1942–43
In early 1942, the governments of smaller powers began to push for an inter-governmental Asia-Pacific war council, based in Washington, D.C. A council was established in London, with a subsidiary body in Washington. However, the smaller powers continued to push for an American-based body. The Pacific War Council was formed in Washington, on 1 April 1942, with President Franklin D. Roosevelt, his key advisor Harry Hopkins, and representatives from Britain, China, Australia, the Netherlands, New Zealand, and Canada. Representatives from India and the Philippines were later added. The council never had any direct operational control, and any decisions it made were referred to the U.S.-UK Combined Chiefs of Staff, which was also in Washington. Allied resistance, at first symbolic, gradually began to stiffen. Australian and Dutch forces led civilians in a prolonged guerilla campaign in Portuguese Timor.

The Doolittle Raid in April 1942, in which bombers took off from the aircraft carrier   from Japan, did minimal material damage but was a huge morale boost for the United States, and it had major psychological repercussions exposing the vulnerabilities of the Japanese homeland. The greatest effect of the raid, however, was that it caused the Japanese to launch the ultimately catastrophic assault on Midway.Wilmott, Barrier and the Javelin

Coral Sea and Midway: the turning point

thumb|right|Lexington on fire at the Coral Sea

By mid-1942, the Japanese found themselves holding a vast area from the Indian Ocean to the Central Pacific, but lacking the resources to defend or sustain it. Moreover, Combined Fleet doctrine was inadequate to execute the proposed "barrier" defense. Instead, Japan decided on additional attacks in both the south and central Pacific. However, the element of surprise, present at Pearl Harbor, was now lost due to the success of Allied codebreakers who had discovered the next attack would be against Port Moresby. If it fell, Japan would control the seas to the north and west of Australia and could isolate the country. The carrier  under Admiral Fletcher joined  and an American-Australian task force to stop the Japanese advance. The resulting Battle of the Coral Sea, fought in May 1942, was the first naval battle in which ships involved never sighted each other and only aircraft were used to attack opposing forces. Although Lexington was sunk and Yorktown seriously damaged, the Japanese lost the carrier , and suffered extensive damage to  and heavy losses to the air wing of , both of which missed the operation against Midway the following month. Although Allied losses were heavier than the Japanese, the attack on Port Moresby was thwarted and the Japanese invasion force turned back in a strategic victory for the Allies. The Japanese were subsequently forced to abandon their attempts to isolate Australia. Moreover, Japan lacked the capacity to replace losses in ships, planes and trained pilots.

thumb|Japanese advance until mid-1942

After Coral Sea, Yamamoto had four fleet carriers operational—, ,  and —and believed Nimitz had a maximum of two— and .  was out of action, undergoing repair after a torpedo attack, while Yorktown had been damaged at Coral Sea, and was believed by Japanese navy intelligence to have been sunk. She would, in fact, sortie for Midway after just three days' of repairs involving her flight deck, with civilian work crews still aboard to be present for the next decisive engagement.

In May, Allied codebreakers again discovered Yamamoto's next move: an attack on Midway Atoll. It was hoped the attack would lure the American carriers into a trap, leading to the destruction of United States strategic power in the Pacific. He also intended to occupy Midway as part of an overall plan to extend Japan's defensive perimeter in response to the Doolittle Raid. It would then be turned into a major airbase, giving Japan control of the central Pacific. 

Initially, a Japanese force was sent north to attack the Aleutian Islands as a diversion. The next stage of the plan called for the capture of Midway, which would give him an opportunity to destroy Nimitz's remaining carriers.  Admiral Nagumo was again in tactical command but was focused on the invasion of Midway; Yamamoto's complex plan had no provision for intervention by Nimitz before the Japanese expected him. Planned surveillance of the U.S. fleet by long range seaplane did not happen (as a result of an abortive identical operation in March), so Fletcher's carriers were able to proceed to a flanking position without being detected. Nagumo had 272 planes operating from his four carriers, the U.S. 348 (115 land-based).

As anticipated by Nimitz, the Japanese fleet arrived off Midway on 4 June and was spotted by PBY patrol aircraft. Nagumo executed a first strike against Midway, while Fletcher launched his aircraft, bound for Nagumo's carriers. At 09:20 the first U.S. carrier aircraft arrived, TBD Devastator torpedo bombers from Hornet, but their attacks were poorly coordinated and ineffectual; thanks in part to faulty aerial torpedoes, they failed to score a single hit and all 15 were wiped out by defending Zero fighters. At 09:35, 15 additional TBDs from Enterprise attacked in which 14 were lost, again with no hits. Thus far, Fletcher's attacks had been disorganized and seemingly ineffectual, but they succeeded in drawing Nagumo's defensive fighters down to sea level where they expended much of their fuel and ammunition repulsing the two waves of torpedo bombers. As a result, when U.S. dive bombers arrived at high altitude, the Zeros were poorly positioned to defend. To make matters worse, Nagumo's four carriers had drifted out of formation in their efforts to avoid torpedoes, reducing the concentration of their anti-aircraft fire. Nagumo's indecision had also created confusion aboard his carriers. Alerted to the need of a second strike on Midway, but also wary of the need to deal with the American carriers that he now knew were in the vicinity, Nagumo twice changed the arming orders for his aircraft. As a result, the American dive bombers found the Japanese carriers with their decks cluttered with munitions as the crews worked hastily to properly re-arm their air groups.

thumb| under attack by B-17 Flying Fortress heavy bombers

With the Japanese CAP out of position and the carriers at their most vulnerable, SBD Dauntlesses from Enterprise and Yorktown appeared at an altitude of  and commenced their attack, quickly dealing fatal blows to three fleet carriers: Sōryū, Kaga, and Akagi. Within minutes, all three were ablaze and had to be abandoned with great loss of life. Hiryū managed to survive the wave of dive bombers and launched a counter-attack against the American carriers which caused severe damage to Yorktown (which was later finished off by a Japanese submarine). However, a second attack from the U.S. carriers a few hours later found and destroyed Hiryū, the last remaining fleet carrier available to Nagumo. With his carriers lost and the Americans withdrawn out of range of his powerful battleships, Yamamoto was forced to call off the operation, leaving Midway in American hands. The battle proved to be a decisive victory for the Allies. For the second time, Japanese expansion had been checked and its formidable Combined Fleet was significantly weakened by the loss of four fleet carriers and many highly trained, virtually irreplaceable, personnel. Japan would be largely on the defensive for the rest of the war.

New Guinea and the Solomons

Japanese land forces continued to advance in the Solomon Islands and New Guinea. From July 1942, a few Australian reserve battalions, many of them very young and untrained, fought a stubborn rearguard action in New Guinea, against a Japanese advance along the Kokoda Track, towards Port Moresby, over the rugged Owen Stanley Ranges. The militia, worn out and severely depleted by casualties, were relieved in late August by regular troops from the Second Australian Imperial Force, returning from action in the Mediterranean theater. In early September 1942 Japanese marines attacked a strategic Royal Australian Air Force base at Milne Bay, near the eastern tip of New Guinea. They were beaten back by Allied (primarily Australian Army) forces.

Guadalcanal
thumb|U.S. Marines rest in the field during the Guadalcanal campaign in November 1942

At the same time as major battles raged in New Guinea, Allied forces identified a Japanese airfield under construction at Guadalcanal. Sixteen thousand Allied infantry, primarily U.S. Marines, made an amphibious landing to capture the airfield in August.

With Japanese and Allied forces occupying various parts of the island, over the following six months both sides poured resources into an escalating battle of attrition on land, at sea, and in the sky. Most of the Japanese aircraft based in the South Pacific were redeployed to the defense of Guadalcanal. Many were lost in numerous engagements with the Allied air forces based at Henderson Field as well as carrier based aircraft. Meanwhile, Japanese ground forces launched repeated attacks on heavily defended US positions around Henderson Field, in which they suffered appalling casualties. To sustain these offensives, resupply was carried out by Japanese convoys, termed the "Tokyo Express" by the Allies. The convoys often faced night battles with enemy naval forces in which they expended destroyers that the IJN could ill-afford to lose. Later fleet battles involving heavier ships and even daytime carrier battles resulted in a stretch of water near Guadalcanal becoming known as "Ironbottom Sound" from the multitude of ships sunk on both sides. However, the Allies were much better able to replace these losses. Finally recognizing that the campaign to recapture Henderson Field and secure Guadalcanal had simply become too costly to continue, the Japanese evacuated the island and withdrew in February 1943.  In the sixth month war of attrition, the Japanese had lost as a result of failing to commit enough forces in sufficient time.

Allied advances in New Guinea and the Solomons
thumb|Australian commandos in New Guinea during July 1943
By late 1942, Japanese headquarters decided to make Guadalcanal their priority. They ordered the Japanese on the Kokoda Track, within sight of the lights of Port Moresby, to retreat to the northeastern coast of New Guinea.  Australian and U.S. forces attacked their fortified positions and after more than two months of fighting in the Buna–Gona area finally captured the key Japanese beachhead in early 1943.

In June 1943, the Allies launched Operation Cartwheel, which defined their offensive strategy in the South Pacific. The operation was aimed at isolating the major Japanese forward base at Rabaul and cutting its supply and communication lines. This prepared the way for Nimitz's island-hopping campaign towards Japan.

Stalemate in China and Southeast Asia
China 1942–1943

thumb|right|Chinese troops during the Battle of Changde in November 1943.
In mainland China, the Japanese 3rd, 6th, and 40th Divisions, a grand total of around 120,000 troops, massed at Yueyang and advanced southward in three columns and crossed the Xinqiang River, and tried again to cross the Miluo River to reach Changsha. In January 1942, Chinese forces got a victory at Changsha which was the first Allied success against Japan..
After the Doolittle Raid, the Japanese army conducted a massive sweep through Zhejiang and Jiangxi of China, now known as the Zhejiang-Jiangxi Campaign, with the goal of searching out the surviving American airmen, applying retribution on the Chinese who aided them and destroying air bases. This operation started on 15 May 1942 with 40 infantry battalions and 15–16 artillery battalions but was repelled by Chinese forces in September. During this campaign, The Imperial Japanese Army left behind a trail of devastation and had also spread cholera, typhoid, plague and dysentery pathogens. Chinese estimates put the death toll at 250,000 civilians. Around 1,700 Japanese troops died out of a total 10,000 Japanese soldiers who fell ill with disease when their own biological weapons attack rebounded on their own forces.Yuki Tanaka, Hidden Horrors, Westviewpres, 1996, p.138Chevrier & Chomiczewski & Garrigue 2004, p.19.Croddy & Wirtz 2005, p. 171. On 2 November 1943, Isamu Yokoyama, commander of the Imperial Japanese 11th Army, deployed the 39th, 58th, 13th, 3rd, 116th and 68th divisions, a grand total of around 100,000 troops, to attack Changde of China. During the seven-week Battle of Changde, the Chinese forced Japan to fight a costly war of attrition.  Although the Japanese army initially successfully captured the city, the Chinese 57th division was able to pin them down long enough for reinforcements to arrive and encircle the Japanese. The Chinese army then cut off the Japanese supply lines, forcing them into retreat, whereupon the Chinese pursued their enemy. During the battle, in an act of desperation, Japan used chemical weapons.Agar, Jon Science in the 20th Century and Beyond, p.281

Burma 1942–1943

In the aftermath of the Japanese conquest of Burma, there was widespread disorder and pro-Independence agitation in eastern India and a disastrous famine in Bengal, which ultimately caused up to 3 million deaths. In spite of these, and inadequate lines of communication, British and Indian forces attempted limited counter-attacks in Burma in early 1943. An offensive in Arakan failed, ignominiously in the view of some senior officers, while a long distance raid mounted by the Chindits under Brigadier Orde Wingate suffered heavy losses, but was publicized to bolster Allied morale. It also provoked the Japanese to mount major offensives themselves the following year.

In August 1943 the Allies formed a new South East Asia Command (SEAC) to take over strategic responsibilities for Burma and India from the British India Command, under Wavell. In October 1943 Winston Churchill appointed Admiral Lord Louis Mountbatten as its Supreme Commander. The British and Indian Fourteenth Army was formed to face the Japanese in Burma. Under Lieutenant General William Slim, its training, morale and health greatly improved. The American General Joseph Stilwell, who also was deputy commander to Mountbatten and commanded U.S. forces in the China Burma India Theater, directed aid to China and prepared to construct the Ledo Road to link India and China by land.

Cairo Conference
On 22 November 1943 U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and ROC Generalissimo Chiang Kai-shek, met in Cairo, Egypt, to discuss a strategy to defeat Japan. The meeting was also known as Cairo Conference and concluded with the Cairo Declaration.

Allied offensives, 1943–44
thumb|left|The Allied leaders of the Asian and Pacific Theaters: Generalissimo Chiang Kai-shek, Franklin D. Roosevelt, and Winston Churchill meeting at the Cairo Conference in 1943
Midway proved to be the last great naval battle for two years. The United States used the ensuing period to turn its vast industrial potential into increased numbers of ships, planes, and trained aircrew. At the same time, Japan, lacking an adequate industrial base or technological strategy, a good aircrew training program, or adequate naval resources and commerce defense, fell further and further behind. In strategic terms the Allies began a long movement across the Pacific, seizing one island base after another. Not every Japanese stronghold had to be captured; some, like Truk, Rabaul, and Formosa, were neutralized by air attack and bypassed. The goal was to get close to Japan itself, then launch massive strategic air attacks, improve the submarine blockade, and finally (only if necessary) execute an invasion.

In November 1943 U.S. Marines sustained high casualties when they overwhelmed the 4,500-strong garrison at Tarawa. This helped the Allies to improve the techniques of amphibious landings, learning from their mistakes and implementing changes such as thorough pre-emptive bombings and bombardment, more careful planning regarding tides and landing craft schedules, and better overall coordination.

The U.S. Navy did not seek out the Japanese fleet for a decisive battle, as Mahanian doctrine would suggest (and as Japan hoped); the Allied advance could only be stopped by a Japanese naval attack, which oil shortages (induced by submarine attack) made impossible.

Submarine warfare

U.S. submarines, as well as some British and Dutch vessels, operating from bases at Cavite in the Philippines (1941–42); Fremantle and Brisbane, Australia; Pearl Harbor; Trincomalee, Ceylon; Midway; and later Guam, played a major role in defeating Japan, even though submarines made up a small proportion of the Allied navies—less than two percent in the case of the US Navy.Theodore Roscoe, United States Submarine Operations in World War II (US Naval Institute Press, 1949). Submarines strangled Japan by sinking its merchant fleet, intercepting many troop transports, and cutting off nearly all the oil imports essential to weapons production and military operations. By early 1945, Japanese oil supplies were so limited that its fleet was virtually stranded.

The Japanese military claimed its defenses sank 468 Allied submarines during the war.Prange et al. Pearl Harbor Papers In reality, only 42 American submarines were sunk in the Pacific due to hostile action, with 10 others lost in accidents or as the result of friendly fire.Roscoe, Theodore. Pig Boats (Bantam Books, 1958); Blair, Silent Victory, pp.991–2. The Dutch lost five submarines due to Japanese attack or minefields,"Boats," www.dutchsubmarines.com and the British lost three.

thumb|right|The torpedoed , as seen through the periscope of an American submarine, , in June 1942

American submarines accounted for 56% of the Japanese merchantmen sunk; mines or aircraft destroyed most of the rest. American submariners also claimed 28% of Japanese warships destroyed.Larry Kimmett and Margaret Regis, U.S. Submarines in World War II Furthermore, they played important reconnaissance roles, as at the battles of the Philippine Sea (June 1944) and Leyte Gulf (October 1944) (and, coincidentally, at Midway in June 1942), when they gave accurate and timely warning of the approach of the Japanese fleet. Submarines also rescued hundreds of downed fliers, including future U.S. president George H. W. Bush.

Allied submarines did not adopt a defensive posture and wait for the enemy to attack. Within hours of the Pearl Harbor attack, in retribution against Japan, Roosevelt promulgated a new doctrine: unrestricted submarine warfare against Japan. This meant sinking any warship, commercial vessel, or passenger ship in Axis-controlled waters, without warning and without aiding survivors. At the outbreak of the war in the Pacific, the Dutch admiral in charge of the naval defense of the East Indies, Conrad Helfrich, gave instructions to wage war aggressively. His small force of submarines sank more Japanese ships in the first weeks of the war than the entire British and US navies together, an exploit which earned him the nickname "Ship-a-day Helfrich". The Dutch force were in fact the first to sink an enemy warship; On 24 December 1941, HNLMS K XVI torpedoed and sank the Japanese destroyer Sagiri.

While Japan had a large number of submarines, they did not make a significant impact on the war. In 1942, the Japanese fleet submarines performed well, knocking out or damaging many Allied warships. However, Imperial Japanese Navy (and pre-war U.S.) doctrine stipulated that only fleet battles, not guerre de course (commerce raiding) could win naval campaigns. So, while the US had an unusually long supply line between its west coast and frontline areas, leaving it vulnerable to submarine attack, Japan used its submarines primarily for long-range reconnaissance and only occasionally attacked US supply lines. The Japanese submarine offensive against Australia in 1942 and 1943 also achieved little.David Stevens. Japanese submarine operations against Australia 1942–1944. Retrieved 18 June 2007.

As the war turned against Japan, IJN submarines increasingly served to resupply strongholds which had been cut off, such as Truk and Rabaul. In addition, Japan honored its neutrality treaty with the Soviet Union and ignored American freighters shipping millions of tons of military supplies from San Francisco to Vladivostok,Carl Boyd, "The Japanese Submarine Force and the Legacy of Strategic and Operational Doctrine Developed Between the World Wars", in Larry Addington ed. Selected Papers from the Citadel Conference on War and Diplomacy: 1978 (Charleston, 1979) 27–40; Clark G. Reynolds, Command of the Sea: The History and Strategy of Maritime Empires (1974) 512. much to the consternation of its German ally.

thumb|right|The , the largest non-nuclear submarines ever constructed.

The US Navy, by contrast, relied on commerce raiding from the outset. However, the problem of Allied forces surrounded in the Philippines, during the early part of 1942, led to diversion of boats to "guerrilla submarine" missions. As well, basing in Australia placed boats under Japanese aerial threat while en route to patrol areas, reducing their effectiveness, and Nimitz relied on submarines for close surveillance of enemy bases. Furthermore, the standard-issue Mark 14 torpedo and its Mark VI exploder both proved defective, problems which were not corrected until September 1943. Worst of all, before the war, an uninformed US Customs officer had seized a copy of the Japanese merchant marine code (called the "maru code" in the USN), not knowing that the Office of Naval Intelligence (ONI) had broken it.Farago, Ladislas. Broken Seal. The Japanese promptly changed it, and the new code was not broken again by OP-20-G until 1943.

Thus, only in 1944 did the US Navy begin to use its 150 submarines to maximum effect: installing effective shipboard radar, replacing commanders deemed lacking in aggression, and fixing the faults in the torpedoes. Japanese commerce protection was "shiftless beyond description," and convoys were poorly organized and defended compared to Allied ones, a product of flawed IJN doctrine and training – errors concealed by American faults as much as Japanese overconfidence. The number of American submarines patrols (and sinkings) rose steeply: 350 patrols (180 ships sunk) in 1942, 350 (335) in 1943, and 520 (603) in 1944.Blair, Silent Victory, pp.359–60, 551–2, & 816. By 1945, sinkings of Japanese vessels had decreased because so few targets dared to venture out on the high seas. In all, Allied submarines destroyed 1,200 merchant ships – about five million tons of shipping. Most were small cargo carriers, but 124 were tankers bringing desperately needed oil from the East Indies. Another 320 were passenger ships and troop transports. At critical stages of the Guadalcanal, Saipan, and Leyte campaigns, thousands of Japanese troops were killed or diverted from where they were needed. Over 200 warships were sunk, ranging from many auxiliaries and destroyers to one battleship and no fewer than eight carriers.

Underwater warfare was especially dangerous; of the 16,000 Americans who went out on patrol, 3,500 (22%) never returned, the highest casualty rate of any American force in World War II. The Joint Army–Navy Assessment Committee assessed U.S. Submarine credits.Roscoe, op. cit. The Japanese losses, 130 submarines in all,Blair, p.877. were even higher.

Japanese counteroffensives in China, 1944

In mid-1944 Japan mobilized over 500,000 men and launched a massive operation across China under the code name Operation Ichi-Go, their largest offensive of World War II, with the goal of connecting Japanese-controlled territory in China and French Indochina and capturing airbases in southeastern China where American bombers were based.Davison, John The Pacific War: Day By Day, pg. 37, 106 During this time,  about 250,000 newest American-trained Chinese troops under Joseph Stilwell and Chinese expeditionary force were forcibly locked in the Burmese theater set by terms of the Lend-Lease Agreement. Though Japan suffered about 100,000 casualties,新聞記者が語りつぐ戦争 16 中国慰霊 読売新聞社 (1983/2) P187 these attacks, the biggest in several years, gained much ground for Japan before Chinese forces stopped the incursions in Guangxi.  Despite major tactical victories, the operation overall failed to provide Japan with any significant strategic gains. A great majority of the Chinese forces were able to retreat out of the area, and later come back to attack Japanese positions such as Battle of West Hunan. Japan was not any closer in defeating China after this operation, and the constant defeats the Japanese suffered in the Pacific meant that Japan never got the time and resources needed to achieve final victory over China. Operation Ichi-go created a great sense of social confusion in the areas of China that it affected. Chinese Communist guerrillas were able to exploit this confusion to gain influence and control of greater areas of the countryside in the aftermath of Ichi-go.China at War: An Encyclopedia. Ed. Li Xiaobing. United States of America: ABC-CLIO. 2012. ISBN 978-1-59884-415-3. Retrieved 21 May 2012. p.163.

Japanese offensive in India, 1944

 thumb|Chinese forces on M3A3 Stuart tanks on the Ledo Road
thumb|British Indian troops during the Battle of Imphal
After the Allied setbacks in 1943, the South East Asia command prepared to launch offensives into Burma on several fronts. In the first months of 1944, the Chinese and American troops of the Northern Combat Area Command (NCAC), commanded by the American Joseph Stilwell, began extending the Ledo Road from India into northern Burma, while the XV Corps began an advance along the coast in the Arakan Province. In February 1944 the Japanese mounted a local counter-attack in the Arakan. After early Japanese success, this counter-attack was defeated when the Indian divisions of XV Corps stood firm, relying on aircraft to drop supplies to isolated forward units until reserve divisions could relieve them.

The Japanese responded to the Allied attacks by launching an offensive of their own into India in the middle of March, across the mountainous and densely forested frontier. This attack, codenamed Operation U-Go, was advocated by Lieutenant General Renya Mutaguchi, the recently promoted commander of the Japanese Fifteenth Army; Imperial General Headquarters permitted it to proceed, despite misgivings at several intervening headquarters. Although several units of the British Fourteenth Army had to fight their way out of encirclement, by early April they had concentrated around Imphal in Manipur state. A Japanese division which had advanced to Kohima in Nagaland cut the main road to Imphal, but failed to capture the whole of the defences at Kohima. During April, the Japanese attacks against Imphal failed, while fresh Allied formations drove the Japanese from the positions they had captured at Kohima.

As many Japanese had feared, Japan's supply arrangements could not maintain her forces. Once Mutaguchi's hopes for an early victory were thwarted, his troops, particularly those at Kohima, starved. During May, while Mutaguchi continued to order attacks, the Allies advanced southwards from Kohima and northwards from Imphal. The two Allied attacks met on 22 June, breaking the Japanese siege of Imphal. The Japanese finally broke off the operation on 3 July. They had lost over 50,000 troops, mainly to starvation and disease. This represented the worst defeat suffered by the Japanese Army to that date.

Although the advance in the Arakan had been halted to release troops and aircraft for the Battle of Imphal, the Americans and Chinese had continued to advance in northern Burma, aided by the Chindits operating against the Japanese lines of communication. In the middle of 1944 the Chinese Expeditionary Force invaded northern Burma from Yunnan. They captured a fortified position at Mount Song. By the time campaigning ceased during the monsoon rains, the NCAC had secured a vital airfield at Myitkyina (August 1944), which eased the problems of air resupply from India to China over "The Hump".

Beginning of the end in the Pacific, 1944

Saipan and Philippine Sea

thumb|The Japanese aircraft carrier Zuikaku and two destroyers under attack in the Battle of the Philippine Sea.
On 15 June 1944, 535 ships began landing 128,000 U.S. Army and Marine personnel on the island of Saipan. The Allied objective was the creation of airfields within B-29 range of Tokyo. The ability to plan and execute such a complex operation in the space of 90 days was indicative of Allied logistical superiority.

It was imperative for Japanese commanders to hold Saipan. The only way to do this was to destroy the U.S. Fifth Fleet, which had 15 fleet carriers and 956 planes, 7 battleships, 28 submarines, and 69 destroyers, as well as several light and heavy cruisers. Vice Admiral Jisaburō Ozawa attacked with nine-tenths of Japan's fighting fleet, which included nine carriers with 473 planes, 5 battleships, several cruisers, and 28 destroyers. Ozawa's pilots were outnumbered 2:1 and their aircraft were becoming or were already obsolete. The Japanese had considerable antiaircraft defenses but lacked proximity fuzes or good radar. With the odds against him, Ozawa devised an appropriate strategy. His planes had greater range because they were not weighed down with protective armor; they could attack at about 480 km (300 mi), and could search a radius of 900 km (560 mi). U.S. Navy Hellcat fighters could only attack within  and only search within a   radius. Ozawa planned to use this advantage by positioning his fleet  out. The Japanese planes would hit the U.S. carriers, land at Guam to refuel, then hit the enemy again when returning to their carriers. Ozawa also counted on about 500 land-based planes at Guam and other islands.

Admiral Raymond A. Spruance was in overall command of Fifth Fleet. The Japanese plan would have failed if the much larger U.S. fleet had closed on Ozawa and attacked aggressively; Ozawa correctly inferred Spruance would not attack. U.S. Admiral Marc Mitscher, in tactical command of Task Force 58, with its 15 carriers, was aggressive but Spruance vetoed Mitscher's plan to hunt down Ozawa because Spruance's orders made protecting the landings on Saipan his first priority.
thumb|Marines fire captured mountain gun during the attack on Garapan, Saipan, 21 June 1944.
The forces converged in the largest sea battle of World War II up to that point. Over the previous month American destroyers had destroyed 17 of 25 submarines out of Ozawa's screening force.Blair, Clay, Jr. Silent Victory (New York: Bantam, 1976).Morison, S. E. U.S. Navy in World War Two. Repeated U.S. raids destroyed the Japanese land-based planes. Ozawa's main attack lacked coordination, with the Japanese planes arriving at their targets in a staggered sequence. Following a directive from Nimitz, the U.S. carriers all had combat information centers, which interpreted the flow of radar data and radioed interception orders to the Hellcats. The result was later dubbed the Great Marianas Turkey Shoot. The few attackers to reach the U.S. fleet encountered massive AA fire with proximity fuzes. Only one American warship was slightly damaged.

On the second day, U.S. reconnaissance planes located Ozawa's fleet,   away, and submarines sank two Japanese carriers. Mitscher launched 230 torpedo planes and dive bombers. He then discovered the enemy was actually another   further off, out of aircraft range (based on a roundtrip flight). Mitscher decided this chance to destroy the Japanese fleet was worth the risk of aircraft losses due to running out of fuel on the return flight. Overall, the U.S. lost 130 planes and 76 aircrew; however, Japan lost 450 planes, three carriers, and 445 aircrew. The Imperial Japanese Navy's carrier force was effectively destroyed.

Leyte Gulf, 1944

The Battle of Leyte Gulf was arguably the largest naval battle in history and was the largest naval battle of World War II. It was a series of four distinct engagements fought off the Philippine island of Leyte from 23 to 26 October 1944. Leyte Gulf featured the largest battleships ever built, was the last time in history that battleships engaged each other, and was also notable as the first time that kamikaze aircraft were used. Allied victory in the Philippine Sea established Allied air and sea superiority in the western Pacific. Nimitz favored blockading the Philippines and landing on Formosa. This would give the Allies control of the sea routes to Japan from southern Asia, cutting off substantial Japanese garrisons. MacArthur favored an invasion of the Philippines, which also lay across the supply lines to Japan. Roosevelt adjudicated in favor of the Philippines. Meanwhile, Japanese Combined Fleet Chief Toyoda Soemu prepared four plans to cover all Allied offensive scenarios. On 12 October Nimitz launched a carrier raid against Formosa to make sure that planes based there could not intervene in the landings on Leyte. Toyoda put Plan Sho-2 into effect, launching a series of air attacks against the U.S. carriers. However the Japanese lost 600 planes in three days, leaving them without air cover.

right|thumbnail|The four engagements in the battle of Leyte Gulf

Sho-1 called for V. Adm. Jisaburō Ozawa's force to use an apparently vulnerable carrier force to lure the U.S. 3rd Fleet away from Leyte and remove air cover from the Allied landing forces, which would then be attacked from the west by three Japanese forces: V. Adm. Takeo Kurita's force would enter Leyte Gulf and attack the landing forces; R. Adm. Shōji Nishimura's force and V. Adm. Kiyohide Shima's force would act as mobile strike forces. The plan was likely to result in the destruction of one or more of the Japanese forces, but Toyoda justified it by saying that there would be no sense in saving the fleet and losing the Philippines.

Kurita's "Center Force" consisted of five battleships, 12 cruisers and 13 destroyers. It included the two largest battleships ever built:  and . As they passed Palawan Island after midnight on 23 October the force was spotted, and U.S. submarines sank two cruisers. On 24 October, as Kurita's force entered the Sibuyan Sea,  and  launched 260 planes, which scored hits on several ships. A second wave of planes scored many direct hits on Musashi. A third wave, from  and  hit Musashi with 11 bombs and eight torpedoes. Kurita retreated but in the evening turned around to head for San Bernardino Strait. Musashi sank at about 19:30.

Meanwhile, V. Adm. Onishi Takijiro had directed his First Air Fleet, 80 land-based planes, against U.S. carriers, whose planes were attacking airfields on Luzon. The carrier  was hit by an armor-piercing bomb and suffered a major explosion which killed 108 crew (out of 1,569) and 233 on the cruiser  which was fire-fighting alongside. Princeton sank, and Birmingham was forced to retire.

Nishimura's force consisted of two battleships, one cruiser and four destroyers. Because they were observing radio silence, Nishimura was unable to synchronize with Shima and Kurita. Nishimura and Shima had failed to even coordinate their plans before the attacks – they were long-time rivals and neither wished to have anything to do with the other. When he entered the narrow Surigao Strait at about 02:00, Shima was 22 miles (40 km) behind him, and Kurita was still in the Sibuyan Sea, several hours from the beaches at Leyte. As they passed Panaon Island, Nishimura's force ran into a trap set for them by the U.S.-Australian 7th Fleet Support Force. R. Adm. Jesse Oldendorf had six battleships, four heavy cruisers, four light cruisers, 29 destroyers and 39 PT boats. To pass the strait and reach the landings, Nishimura had to run the gauntlet. At about 03:00 the Japanese battleship  and three destroyers were hit by torpedoes and Fusō broke in two. At 03:50 the U.S. battleships opened fire. Radar fire control meant they could hit targets from a much greater distance than the Japanese. The battleship , a cruiser and a destroyer were crippled by 16-inch (406 mm) shells; Yamashiro sank at 04:19. Only one of Nishimura's force of seven ships survived the engagement. At 04:25 Shima's force of two cruisers and eight destroyers reached the battle. Seeing Fusō and believing her to be the wrecks of two battleships, Shima ordered a retreat, ending the last battleship-vs-battleship action in history.

Ozawa's "Northern Force" had four aircraft carriers, two obsolete battleships partly converted to carriers, three cruisers and nine destroyers. The carriers had only 108 planes. The force was not spotted by the Allies until 16:40 on 24 October. At 20:00 Toyoda ordered all remaining Japanese forces to attack. Halsey saw an opportunity to destroy the remnants of the Japanese carrier force. The U.S. Third Fleet was formidable – nine large carriers, eight light carriers, six battleships, 17 cruisers, 63 destroyers and 1,000 planes – and completely outgunned Ozawa's force. Halsey's ships set out in pursuit of Ozawa just after midnight. U.S. commanders ignored reports that Kurita had turned back towards San Bernardino Strait. They had taken the bait set by Ozawa. On the morning of 25 October Ozawa launched 75 planes. Most were shot down by U.S. fighter patrols. By 08:00 U.S. fighters had destroyed the screen of Japanese fighters and were hitting ships. By evening, they had sunk the carriers , , and , and a destroyer. The fourth carrier, , and a cruiser were disabled and later sank.
thumb|The Japanese aircraft carriers , left, and (probably)  come under attack by dive bombers early in the battle off Cape Engaño.

Kurita passed through San Bernardino Strait at 03:00 on 25 October and headed along the coast of Samar. The only thing standing in his path were three groups (Taffy 1, 2 and 3) of the Seventh Fleet, commanded by Admiral Thomas Kinkaid. Each group had six escort carriers, with a total of more than 500 planes, and seven or eight destroyers or destroyer escorts (DE). Kinkaid still believed that Lee's force was guarding the north, so the Japanese had the element of surprise when they attacked Taffy 3 at 06:45. Kurita mistook the Taffy carriers for large fleet carriers and thought he had the whole Third Fleet in his sights. Since escort carriers stood little chance against a battleship, Adm. Clifton Sprague directed the carriers of Taffy 3 to turn and flee eastward, hoping that bad visibility would reduce the accuracy of Japanese gunfire, and used his destroyers to divert the Japanese battleships. The destroyers made harassing torpedo attacks against the Japanese. For ten minutes Yamato was caught up in evasive action. Two U.S. destroyers and a DE were sunk, but they had bought enough time for the Taffy groups to launch planes. Taffy 3 turned and fled south, with shells scoring hits on some of its carriers and sinking one of them. The superior speed of the Japanese force allowed it to draw closer and fire on the other two Taffy groups. However, at 09:20 Kurita suddenly turned and retreated north. Signals had disabused him of the notion that he was attacking the Third Fleet, and the longer Kurita continued to engage, the greater the risk of major air strikes. Destroyer attacks had broken the Japanese formations, shattering tactical control. Three of Kurita's heavy cruisers had been sunk and another was too damaged to continue the fight. The Japanese retreated through the San Bernardino Strait, under continuous air attack. The Battle of Leyte Gulf was over; and a large part of the Japanese surface fleet destroyed.

The battle secured the beachheads of the U.S. Sixth Army on Leyte against attack from the sea, broke the back of Japanese naval power and opened the way for an advance to the Ryukyu Islands in 1945. The only significant Japanese naval operation afterwards was the disastrous Operation Ten-Go in April 1945. Kurita's force had begun the battle with five battleships; when he returned to Japan, only Yamato was combat-worthy. Nishimura's sunken Yamashiro was the last battleship in history to engage another in combat.

Philippines, 1944–45
thumb|General Douglas MacArthur wading ashore at Leyte

On 20 October 1944 the U.S. Sixth Army, supported by naval and air bombardment, landed on the favorable eastern shore of Leyte, north of Mindanao. The U.S. Sixth Army continued its advance from the east, as the Japanese rushed reinforcements to the Ormoc Bay area on the western side of the island. While the Sixth Army was reinforced successfully, the U.S. Fifth Air Force was able to devastate the Japanese attempts to resupply. In torrential rains and over difficult terrain, the advance continued across Leyte and the neighboring island of Samar to the north. On 7 December U.S. Army units landed at Ormoc Bay and, after a major land and air battle, cut off the Japanese ability to reinforce and supply Leyte. Although fierce fighting continued on Leyte for months, the U.S. Army was in control.

On 15 December 1944 landings against minimal resistance were made on the southern beaches of the island of Mindoro, a key location in the planned Lingayen Gulf operations, in support of major landings scheduled on Luzon. On 9 January 1945, on the south shore of Lingayen Gulf on the western coast of Luzon, General Krueger's Sixth Army landed his first units. Almost 175,000 men followed across the twenty-mile (32 km) beachhead within a few days. With heavy air support, Army units pushed inland, taking Clark Field,  northwest of Manila, in the last week of January.
thumb|U.S. troops approaching Japanese positions near Baguio, Luzon, 23 March 1945
Two more major landings followed, one to cut off the Bataan Peninsula, and another, that included a parachute drop, south of Manila. Pincers closed on the city and, on 3 February 1945, elements of the 1st Cavalry Division pushed into the northern outskirts of Manila and the 8th Cavalry passed through the northern suburbs and into the city itself.

As the advance on Manila continued from the north and the south, the Bataan Peninsula was rapidly secured. On 16 February paratroopers and amphibious units assaulted the island fortress of Corregidor, and resistance ended there on 27 February.

In all, ten U.S. divisions and five independent regiments battled on Luzon, making it the largest campaign of the Pacific war, involving more troops than the United States had used in North Africa, Italy, or southern France. Of the 250,000 Japanese troops defending Luzon, 80 percent died. The last Japanese soldier in the Philippines to surrender was Hiroo Onoda on 9 March 1974.Powers, D. (2011): Japan: No Surrender in World War Two BBC History (17 February 2011).

Palawan Island, between Borneo and Mindoro, the fifth largest and western-most Philippine Island, was invaded on 28 February with landings of the Eighth Army at Puerto Princesa. The Japanese put up little direct defense of Palawan, but cleaning up pockets of Japanese resistance lasted until late April, as the Japanese used their common tactic of withdrawing into the mountain jungles, dispersed as small units. Throughout the Philippines, U.S. forces were aided by Filipino guerrillas to find and dispatch the holdouts.

The U.S. Eighth Army then moved on to its first landing on Mindanao (17 April), the last of the major Philippine Islands to be taken. Mindanao was followed by invasion and occupation of Panay, Cebu, Negros and several islands in the Sulu Archipelago. These islands provided bases for the U.S. Fifth and Thirteenth Air Forces to attack targets throughout the Philippines and the South China Sea.

Final stages

thumb|Iwo Jima Location Map

Iwo Jima, February 1945

The battle of Iwo Jima ("Operation Detachment") in February 1945 was one of the bloodiest battles fought by the Americans in the Pacific War. Iwo Jima is an 8 sq mile (21 km2) island situated halfway between Tokyo and the Mariana Islands. Holland Smith, the commander of the invasion force, aimed to capture the island, and utilize its three airfields as bases to carry out air attacks against the Home Islands. Lt. General Tadamichi Kuribayashi, the commander of the island's defense, knew that he could not win the battle, but he hoped to make the Americans suffer far more than they could endure.

From early 1944 until the days leading up to the invasion, Kuribayashi transformed the island into a massive network of bunkers, hidden guns, and 11 mi (18 km) of underground tunnels. The heavy American naval and air bombardment did little but drive the Japanese further underground, making their positions impervious to enemy fire. Their pillboxes and bunkers were all connected so that if one was knocked out, it could be reoccupied again. The network of bunkers and pillboxes greatly favored the defender.

Starting in mid-June 1944, Iwo Jima came under sustained aerial bombardment and naval artillery fire. However, Kuribayashi's hidden guns and defenses survived the constant bombardment virtually unscathed. On 19 February 1945, some 30,000 men of the 3rd, 4th, and 5th Marine Divisions landed on the southeast coast of Iwo, just under Mount Suribachi; where most of the island's defenses were concentrated. For some time, they did not come under fire. This was part of Kuribayashi's plan to hold fire until the landing beaches were full. As soon as the Marines pushed inland to a line of enemy bunkers, they came under devastating machine gun and artillery fire which cut down many of the men. By the end of the day, the Marines reached the west coast of the island, but their losses were appalling; almost 2,000 men killed or wounded.

On 23 February, the 28th Marine Regiment reached the summit of Suribachi, prompting the now famous Raising the Flag on Iwo Jima picture. Navy Secretary James Forrestal, upon seeing the flag, remarked "there will be a Marine Corps for the next 500 years".  The flag raising is often cited as the most reproduced photograph of all time and became the archetypal representation not only of that battle, but of the entire Pacific War. For the rest of February, the Americans pushed north, and by 1 March, had taken two-thirds of the island. But it was not until 26 March that the island was finally secured. The Japanese fought to the last man, killing 6,800 Marines and wounding nearly 20,000 more. The Japanese losses totaled well over 20,000 men killed, and only 1,083 prisoners were taken. Historians debate whether it was strategically worth the casualties sustained.Robert S. Burrell, "Breaking the Cycle of Iwo Jima Mythology: A Strategic Study of Operation Detachment," Journal of Military History Volume 68, Number 4, October 2004, pp. 1143–1186 and rebuttal in Project MUSE

Allied offensives in Burma, 1944–45

right|thumb|British Royal Marines land at Ramree
In late 1944 and early 1945, the Allied South East Asia Command launched offensives into Burma, intending to recover most of the country, including Rangoon, the capital, before the onset of the monsoon in May.

The Indian XV Corps advanced along the coast in Arakan province, at last capturing Akyab Island after failures in the two previous years. They then landed troops behind the retreating Japanese, inflicting heavy casualties, and captured Ramree Island and Cheduba Island off the coast, establishing airfields on them which were used to support the offensive into Central Burma.

The Chinese Expeditionary Force captured Mong-Yu and Lashio,. while the Chinese and American Northern Combat Area Command resumed its advance in northern Burma. In late January 1945, these two forces linked up with each other at Hsipaw. The Ledo Road was completed, linking India and China, but too late in the war to have any significant effect.

The Japanese Burma Area Army attempted to forestall the main Allied attack on the central part of the front by withdrawing their troops behind the Irrawaddy River. Lieutenant General Heitarō Kimura, the new Japanese commander in Burma, hoped that the Allies' lines of communications would be overstretched trying to cross this obstacle. However, the advancing British Fourteenth Army under Lieutenant General William Slim switched its axis of advance to outflank the main Japanese armies.

During February, Fourteenth Army secured bridgeheads across the Irrawaddy on a broad front. On 1 March, units of IV Corps captured the supply centre of Meiktila, throwing the Japanese into disarray. While the Japanese attempted to recapture Meiktila, XXXIII Corps captured Mandalay. The Japanese armies were heavily defeated, and with the capture of Mandalay, the Burmese population and the Burma National Army (which the Japanese had raised) turned against the Japanese.

During April, Fourteenth Army advanced  south towards Rangoon, the capital and principal port of Burma, but was delayed by Japanese rearguards  north of Rangoon at the end of the month. Slim feared that the Japanese would defend Rangoon house-to-house during the monsoon, placing his army in a disastrous supply situation, and in March he had asked that a plan to capture Rangoon by an amphibious force, Operation Dracula, which had been abandoned earlier, be reinstated. Dracula was launched on 1 May, but Rangoon was found to have been abandoned. The troops which occupied Rangoon linked up with Fourteenth Army five days later, securing the Allies' lines of communication.

The Japanese forces which had been bypassed by the Allied advances attempted to break out across the Sittaung River during June and July to rejoin the Burma Area Army which had regrouped in Tenasserim in southern Burma. They suffered 14,000 casualties, half their strength. Overall, the Japanese lost some 150,000 men in Burma. Only 1,700 prisoners were taken.

The Allies were preparing to make amphibious landings in Malaya when word of the Japanese surrender arrived.

Liberation of Borneo
thumb|U.S. LVTs land Australian soldiers at Balikpapan on 7 July 1945

The Borneo Campaign of 1945 was the last major campaign in the South West Pacific Area. In a series of amphibious assaults between 1 May and 21 July, the Australian I Corps, under General Leslie Morshead, attacked Japanese forces occupying the island. Allied naval and air forces, centered on the U.S. 7th Fleet under Admiral Thomas Kinkaid, the Australian First Tactical Air Force and the U.S. Thirteenth Air Force also played important roles in the campaign.

The campaign opened with a landing on the small island of Tarakan on 1 May. This was followed on 1 June by simultaneous assaults in the north west, on the island of Labuan and the coast of Brunei. A week later the Australians attacked Japanese positions in North Borneo. The attention of the Allies then switched back to the central east coast, with the last major amphibious assault of World War II, at Balikpapan on 1 July.

Although the campaign was criticized in Australia at the time, and in subsequent years, as pointless or a "waste" of the lives of soldiers, it did achieve a number of objectives, such as increasing the isolation of significant Japanese forces occupying the main part of the Dutch East Indies, capturing major oil supplies and freeing Allied prisoners of war, who were being held in deteriorating conditions.. Pages 184–186. At one of the very worst sites, around Sandakan in Borneo, only six of some 2,500 British and Australian prisoners survived.

China, 1945

By April 1945, China had already been at war with Japan for more than seven years. Both nations were exhausted by years of battles, bombings and blockades. After Japanese victories in Operation Ichi-Go, Japan were losing the battle in Burma and facing constant attacks from Chinese Nationalists forces and Communist guerrillas in the country side. The Japanese army began preparations for the Battle of West Hunan in March 1945. Japanese mobilized 34th, 47th, 64th, 68th and 116th Divisions, as well as the 86th Independent Brigade, for a total of 80,000 men to seize Chinese airfields and secure railroads in West Hunan by early April.Wilson, Dick. When Tigers Fight. New York, NY: The Viking Press, 1982. pp. 248 In response, the Chinese National Military Council dispatched the 4th Front Army and the 10th and 27th Army Groups with He Yingqin as commander-in-chief.. At the same time, it airlifted the entire Chinese New 6th Corps, an American-equipped corps and veterans of the Burma Expeditionary Force, from Kunming to Zhijiang. Chinese forces totaled 110,000 men in 20 divisions. They were supported by about 400 aircraft from Chinese and American air forces."National Revolutionary Army Order of Battle for the Battle of West Hunan". China Whampoa Academy Net. 11 September 2007 <http://www.hoplite.cn/Templates/hpjh0106.htm>. Chinese forces achieved a decisive victory and launched a large counterattack in this campaign. Concurrently, the Chinese managed to repel a Japanese offensive in Henan and Hubei. Afterwards, Chinese forces retook Hunan and Hubei provinces in South China. Chinese launched a counter offensive to retake Guangxi which was the last major Japanese stronghold in South China. In August 1945, Chinese forces successfully retook Guangxi.

Okinawa
thumb| burns after being hit by two kamikazes. At Okinawa the kamikazes caused 4,900 American deaths.

The largest and bloodiest American battle came at Okinawa, as the U.S. sought airbases for 3,000 B-29 bombers and 240 squadrons of B-17 bombers for the intense bombardment of Japan's home islands in preparation for a full-scale invasion in late 1945. The Japanese, with 115,000 troops augmented by thousands of civilians on the heavily populated island, did not resist on the beaches—their strategy was to maximize the number of soldier and Marine casualties, and naval losses from Kamikaze attacks. After an intense bombardment the Americans landed on 1 April 1945 and declared victory on 21 June.Joseph H. Alexander, The final campaign: Marines in the victory on Okinawa (1996) short official history online The supporting naval forces were the targets for 4,000 sorties, many by Kamikaze suicide planes. U.S. losses totaled 38 ships of all types sunk and 368 damaged with 4,900 sailors killed. The Americans suffered 75,000 casualties on the ground; 94% of the Japanese soldiers died along with many civilians.Hiromichi Yahara, The Battle For Okinawa (1997), Japanese perspective excerpt and text search

The British Pacific Fleet operated as a separate unit from the American task forces in the Okinawa operation. Its objective was to strike airfields on the chain of islands between Formosa and Okinawa, to prevent the Japanese reinforcing the defences of Okinawa from that direction.

 Landings in the Japanese home islands 

Hard-fought battles on the Japanese home islands of Iwo Jima, Okinawa, and others resulted in horrific casualties on both sides but finally produced a Japanese defeat. Of the 117,000 Japanese troops defending Okinawa, 94 percent died."Creating military power: the sources of military effectiveness". Risa Brooks, Elizabeth A. Stanley (2007). Stanford University Press. p.41. ISBN 0-8047-5399-7 Faced with the loss of most of their experienced pilots, the Japanese increased their use of kamikaze tactics in an attempt to create unacceptably high casualties for the Allies. The U.S. Navy proposed to force a Japanese surrender through a total naval blockade and air raids.Skates, James. Invasion of Japan.
thumb|upright|left|The mushroom cloud from the nuclear explosion over Nagasaki rising 60,000 feet (18 km) into the air on the morning of 9 August 1945.

Towards the end of the war as the role of strategic bombing became more important, a new command for the U.S. Strategic Air Forces in the Pacific was created to oversee all U.S. strategic bombing in the hemisphere, under United States Army Air Forces General Curtis LeMay. Japanese industrial production plunged as nearly half of the built-up areas of 67 cities were destroyed by B-29 firebombing raids. On 9–10 March 1945 alone, about 100,000 people were killed in a conflagration caused by an incendiary attack on Tokyo. LeMay also oversaw Operation Starvation, in which the inland waterways of Japan were extensively mined by air, which disrupted the small amount of remaining Japanese coastal sea traffic. On 26 July 1945, the President of the United States Harry S. Truman, the President of the Nationalist Government of China Chiang Kai-shek and the Prime Minister of Great Britain Winston Churchill issued the Potsdam Declaration, which outlined the terms of surrender for the Empire of Japan as agreed upon at the Potsdam Conference. This ultimatum stated that, if Japan did not surrender, it would face "prompt and utter destruction."

The Atomic bomb

On 6 August 1945, the U.S. dropped an atomic bomb on the Japanese city of Hiroshima in the first nuclear attack in history. In a press release issued after the atomic bombing of Hiroshima, Truman warned Japan to surrender or "...expect a rain of ruin from the air, the like of which has never been seen on this earth." Three days later, on 9 August, the U.S. dropped another atomic bomb on Nagasaki, the last nuclear attack in history. More than 140,000–240,000 people died as a direct result of these two bombings.Professor Duncan Anderson, 2005,"Nuclear Power: The End of the War Against Japan" (World War Two, BBC History website) Access date: 11 September 2007. The necessity of the atomic bombings has long been debated, with detractors claiming that a naval blockade and aerial bombing campaign had already made invasion, hence the atomic bomb, unnecessary.See, for example, Alperowitz, G., The Decision to Use the Atomic Bomb (1995; New York, Knopf; ISBN 0-679-44331-2) for this argument. However, other scholars have argued that the bombings shocked the Japanese government into surrender, with Emperor finally indicating his wish to stop the war. Another argument in favor of the atomic bombs is that they helped avoid Operation Downfall, or a prolonged blockade and bombing campaign, any of which would have exacted much higher casualties among Japanese civilians. Historian Richard B. Frank wrote that a Soviet invasion of Japan was never likely because they had insufficient naval capability to mount an amphibious invasion of Hokkaidō.

Soviet invasion of Manchuria
thumb|right|Pacific Fleet marines of the Soviet Navy hoisting the Soviet naval ensign in Port Arthur, on 1 October 1945.

On 3 February 1945 the Soviet Union agreed with Roosevelt to enter the Pacific conflict. It promised to act 90 days after the war ended in Europe and did so exactly on schedule on 9 August by invading Manchuria. A battle-hardened, one million-strong Soviet force, transferred from Europe, attacked Japanese forces in Manchuria and landed a heavy blow against the Japanese Kantōgun (Kwantung Army).Raymond L. Garthoff. The Soviet Manchurian Campaign, August 1945. Military Affairs, Vol. 33, No. 2 (Oct. 1969), pp. 312–336

The Manchurian Strategic Offensive Operation began on 9 August 1945, with the Soviet invasion of the Japanese puppet state of Manchukuo and was the last campaign of the Second World War and the largest of the 1945 Soviet–Japanese War which resumed hostilities between the Soviet Union and the Empire of Japan after almost six years of peace. Soviet gains on the continent were Manchukuo, Mengjiang (Inner Mongolia) and northern Korea. The USSR's early entry into the war was a significant factor in the Japanese decision to surrender as it became apparent the Soviets were no longer willing to act as an intermediary for a negotiated settlement on favorable terms.

Surrender

thumb|Douglas MacArthur signs the formal Japanese Instrument of Surrender on the , 2 September 1945.

The effects of the "Twin Shocks"—the Soviet entry and the atomic bombing—were profound. On 10 August the "sacred decision" was made by Japanese Cabinet to accept the Potsdam terms on one condition: the "prerogative of His Majesty as a Sovereign Ruler". At noon on 15 August, after the American government's intentionally ambiguous reply, stating that the "authority" of the emperor "shall be subject to the Supreme Commander of the Allied Powers", the Emperor broadcast to the nation and to the world at large the rescript of surrender,Sadao Asada. "The Shock of the Atomic Bomb and Japan's Decision to Surrender: A Reconsideration". The Pacific Historical Review, Vol. 67, No. 4 (Nov. 1998), pp. 477–512. ending the Second World War.

In Japan, 14 August is considered to be the day that the Pacific War ended. However, as Imperial Japan actually surrendered on 15 August, this day became known in the English-speaking countries as "V-J Day" (Victory in Japan). The formal Japanese Instrument of Surrender was signed on 2 September 1945, on the battleship , in Tokyo Bay. The surrender was accepted by General Douglas MacArthur as Supreme Commander for the Allied Powers, with representatives of several Allied nations, from a Japanese delegation led by Mamoru Shigemitsu and Yoshijirō Umezu.

Following this period, MacArthur went to Tokyo to oversee the postwar development of the country. This period in Japanese history is known as the occupation.

War crimes

thumb|upright|Australian POW moments before his execution

On 7 December 1941, 2,403 non-combatants (2,335 neutral military personnel and 68 civilians) were killed and 1,247 wounded during the Japanese surprise attack on Pearl Harbor. Because the attack happened without a declaration of war and without explicit warning, it was judged by the Tokyo Trials to be a war crime.

During the Pacific War, Japanese soldiers killed millions of non-combatants, including prisoners of war, from surrounding nations. At least 20 million Chinese died during the Sino-Japanese War (1937–1945).

Unit 731 was one example of wartime atrocities committed on a civilian population during World War II, where experiments were performed on thousands of Chinese civilians and Allied prisoners of war. In military campaigns, the Japanese Army used biological weapons and chemical weapons on the Chinese, killing around 400,000 civilians. The Rape of Nanking is another example of atrocity committed by Japanese soldiers on a civilian population.
thumb|Chinese corpses in a ditch after being killed by the Japanese Army, Hsuchow
According to the findings of the Tokyo Tribunal, the death rate of Western prisoners was 27.1%, seven times that of POWs under the Germans and Italians."Japanese prisoners of war". Philip Towle, Margaret Kosuge, Yōichi Kibata (2000). Continuum International Publishing Group. pp.47–48. ISBN 1-85285-192-9. The most notorious use of forced labour was in the construction of the Burma–Thailand Death Railway. Around 1,536 U.S. civilians were killed or otherwise died of abuse and mistreatment in Japanese interment camps in the Far East; in comparison, only 883 U.S. civilians died in German internment camps in Europe.U.S. Prisoners of War and Civilian American Citizens Captured and Interned by Japan in World War II: The Issue of Compensation by Japan.

A widely publicised example of institutionalised sexual slavery are "comfort women", a euphemism for the 200,000 women, mostly from Korea and China, who served in the Japanese army's camps during World War II. Some 35 Dutch comfort women brought a successful case before the Batavia Military Tribunal in 1948. In 1993, Chief Cabinet Secretary Yōhei Kōno said that women were coerced into brothels run by Japan's wartime military. Other Japanese leaders have apologized, including former Prime Minister Junichiro Koizumi in 2001. In 2007, then-Prime Minister Shinzō Abe asserted: "The fact is, there is no evidence to prove there was coercion.""No government coercion in war's sex slavery: Abe", The Japan Times, 2 March 2007.

The Three Alls Policy (Sankō Sakusen) was a Japanese scorched earth policy adopted in China, the three alls being: "Kill All, Burn All and Loot All". Initiated in 1940 by Ryūkichi Tanaka, the Sankō Sakusen was implemented in full scale in 1942 in north China by Yasuji Okamura. According to historian Mitsuyoshi Himeta, the scorched earth campaign was responsible for the deaths of "more than 2.7 million" Chinese civilians.Himeta, Mitsuyoshi (姫田光義) (日本軍による『三光政策・三光作戦をめぐって』) (Concerning the Three Alls Strategy/Three Alls Policy By the Japanese Forces), Iwanami Bukkuretto, 1996, Bix, Hirohito and the Making of Modern Japan, 2000.

The collection of skulls and other remains of Japanese soldiers by allied soldiers was shown by several studies to have been widespread enough to be commented upon by Allied military authorities and U.S. wartime press."Simon Harrison, Dark Trophies: hunting and the enemy body in modern war, Berghahn Booksl, 2012

Following the defeat of Japan, the International Military Tribunal for the Far East took place in Ichigaya, Tokyo from 29 April 1946 to 12 November 1948 to try those accused of the most serious war crimes. Meanwhile, military tribunals were also held by the returning powers throughout Asia and the Pacific for lesser figures.Dennis et al. 2008, pp. 576–577.McGibbon 2000, pp. 580–581.

 See also 

 European theatre of World War II
 Pacific War campaigns
 Japanese holdout
 Operation Downfall
 Timeline WW II – Pacific Theater
 Yasukuni Shrine

 Notes 

 References 
 Citations 

 Sources 

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 Buell, Thomas.  The Quiet Warrior: A Biography of Admiral Raymond Spruance. 1974.
 
 Channel 4 (UK). Hell in the Pacific (television documentary series). 2001.
 Costello, John. The Pacific War. 1982, overview
 Craven, Wesley, and James Cate, eds. The Army Air Forces in World War II. Vol. 1, Plans and Early Operations, January 1939 to August 1942. University of Chicago Press, 1958. Official history; Vol. 4, The Pacific: Guadalcanal to Saipan, August 1942 to July 1944. 1950; Vol. 5, The Pacific: Matterhorn to Nagasaki. 1953.
 
 
 Dunnigan, James F., and Albert A. Nofi. The Pacific War Encyclopedia. Facts on File, 1998. 2 vols. 772p.
 
 Gailey, Harry A. The War in the Pacific: From Pearl Harbor to Tokyo Bay (1995) online
 
 Gordon, David M. "The China-Japan War, 1931–1945" Journal of Military History (January 2006) v 70#1, pp 137–82. Historiographical overview of major books
 Seki, Eiji. (2006). Mrs. Ferguson's Tea-Set, Japan and the Second World War: The Global Consequences Following Germany's Sinking of the SS Automedon in 1940. London: Global Oriental.  ISBN 978-1-905246-28-1 (cloth) (reprinted by University of Hawaii Press), Honolulu, 2007. previously announced as Sinking of the SS Automedon and the Role of the Japanese Navy: A New Interpretation.
 
 
 
 Saburo Hayashi and Alvin Coox. Kogun: The Japanese Army in the Pacific War. Quantico, Virginia: Marine Corps Assoc., 1959.
 
 Hsiung, James C. and Steven I. Levine, eds. China's Bitter Victory: The War with Japan, 1937–1945 M. E. Sharpe, 1992
 Hsi-sheng, Ch'i. Nationalist China at War: Military Defeats and Political Collapse, 1937–1945 University of Michigan Press, 1982
 Hsu Long-hsuen and Chang Ming-kai, History of The Sino-Japanese War (1937–1945), 2nd Ed., 1971. Translated by Wen Ha-hsiung, Chung Wu Publishing; 33, 140th Lane, Tung-hwa Street, Taipei, Taiwan Republic of China.
 Inoguchi, Rikihei, Tadashi Nakajima, and Robert Pineau. The Divine Wind. Ballantine, 1958. Kamikaze.
 James, D. Clayton. The Years of MacArthur. Vol. 2. Houghton Mifflin, 1972.
 
 
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 Maurice Matloff and Edwin M. Snell Strategic Planning for Coalition Warfare 1941–1942, United States Army Center of Military History, Washington, D. C., 1990
 
 
 
 
 Samuel Eliot Morison, History of United States Naval Operations in World War II. Vol. 3, The Rising Sun in the Pacific. Boston: Little, Brown, 1961; Vol. 4, Coral Sea, Midway and Submarine Actions. 1949; Vol. 5, The Struggle for Guadalcanal. 1949; Vol. 6, Breaking the Bismarcks Barrier. 1950; Vol. 7, Aleutians, Gilberts, and Marshalls. 1951; Vol. 8, New Guinea and the Marianas. 1962; Vol. 12, Leyte. 1958; vol. 13, The Liberation of the Philippines: Luzon, Mindanao, the Visayas. 1959; Vol. 14, Victory in the Pacific. 1961.
 
 Masatake Okumiya, and Mitso Fuchida. Midway: The Battle That Doomed Japan. Naval Institute Press, 1955.
 E. B. Potter, and Chester W. Nimitz. Triumph in the Pacific. Prentice Hall, 1963. Naval battles
 E. B. Potter, Bull Halsey Naval Institute Press, 1985.
 E. B. Potter, Nimitz. Annapolis, Maryland: Naval Institute Press, 1976.
 John D. Potter, Yamamoto 1967.
 Gordon W. Prange, Donald Goldstein, and Katherine Dillon. At Dawn We Slept. Penguin, 1982. Pearl Harbor
 ——, et al. Miracle at Midway. Penguin, 1982.
 ——, et al. Pearl Harbor: The Verdict of History.
 
 Henry Shaw, and Douglas Kane. History of U.S. Marine Corps Operations in World War II. Vol. 2, Isolation of Rabaul. Washington, D.C.: Headquarters, U.S. Marine Corps, 1963
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 E.B. Sledge, With the Old Breed: At Peleliu and Okinawa. Presidio, 1981. Memoir.
 J. Douglas Smith, and Richard Jensen. World War II on the Web: A Guide to the Very Best Sites. (2002)
 Ronald Spector, Eagle Against the Sun: The American War with Japan Free Press, 1985.
 John Toland, The Rising Sun. 2 vols. Random House, 1970. Japan's war.
 Ian W. Toll. Pacific Crucible: War at Sea in the Pacific, 1941–1942 (2011)

 H. P. Willmott. Empires in the Balance. Annapolis: United States Naval Institute Press, 1982.
 H. P. Willmott.  The Barrier and the Javelin. Annapolis: United States Naval Institute Press, 1983.
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 William Y'Blood, Red Sun Setting: The Battle of the Philippine Sea. Annapolis, Maryland: Naval Institute Press, 1980.
 
 

 Further reading 
 

 External links 

 "The Pacific War Online Encyclopedia" compiled by Kent G. Budge, 4000 short articles
 Film Footage of the Pacific War
 Animated History of the Pacific War
 The Pacific War Series – at The War Times Journal
 Morinoske: Japanese Pilot testimonials – and more
 Imperial Japanese Navy Page
 

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War
Category:World War II theatres involving the United Kingdom