Days after the beginning of the war, General of the Army Douglas MacArthur, the US Army officer in command of all UN forces in Korea, envisioned an amphibious assault to retake the Seoul area. The city had fallen in the first days of the war in the First Battle of Seoul. MacArthur later wrote that he thought the KPA would push the ROK back far past Seoul. He also said he decided days after the war began that the battered, demoralized, and under-equipped ROK, many of whom did not support the South Korean government put in power by the United States, could not hold off the KPA even with American support. MacArthur felt that he could turn the tide if he made a decisive troop movement behind KPA lines, and preferred Inchon, over Chumunjin-up or Kunsan as the landing site. He had originally envisioned such a landing, code named Operation Bluehearts, for 22 July, with the US Army's 1st Cavalry Division landing at Inchon. However, by 10 July the plan was abandoned as it was clear the 1st Cavalry Division would be needed on the Pusan Perimeter. On 23 July, MacArthur formulated a new plan, code-named Operation Chromite, calling for an amphibious assault by the US Army's 2nd Infantry Division and the United States Marine Corps (USMC)'s 5th Marine Regiment in mid-September 1950. This, too fell through as both units were moved to the Pusan Perimeter. MacArthur decided instead to use the US Army's 7th Infantry Division, his last reserve unit in East Asia, to conduct the operation as soon as it could be raised to wartime strength.