World War II marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war. Japan, which aimed to dominate Asia and the Pacific, was at war with China by 1937, though neither side had declared war on the other. World War II is generally said to have begun on 1 September 1939, with the invasion of Poland by Germany and subsequent declarations on Germany by France and the United Kingdom. From
Scuba diving fatalities for determining overall fatality rates, and the population estimates from the 1990s of several million U.S. divers need to be updated. The most frequent root cause for diving fatalities is running out of or low on gas. Other factors cited include buoyancy control, entanglement or entrapment, rough water, equipment misuse or problems and emergency ascent. The most common injuries and causes of death were drowning or asphyxia due to inhalation of water, air embolism and cardiac events. Risk of cardiac arrest is greater for older divers, and greater for men than women, although the risks are equal by age 65.