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More than 28 million men and women were organized into the Patriotic Citizens Fighting Corps, which in addition to the 900,000 soldiers remaining in the Imperial Japanese Army, would have fought ferociously to protect their homes and national honor from the invading Americans. The United States knew of this excepted ferocity, and projected enormously high casualties for the operations. The Joint Chiefs of Staff conducted a study that found that a ninety-day Olympic campaign would cost 456,000 casualties, including 109,000 soldiers killed; and that if Coronet operated under the same timetable as Olympic, the U.S. would suffer 1,200,000 casualties, including 267,000 fatalities. A letter sent to General Curtis LeMay stated that in an invasion took place, it would cost the U.S. "half a million dead" (Coffey, 474).
Those numbers: 1,656,000 casualties, and up to 376,000 American soldiers killed in action, are nothing short of staggering. The amount of lives that would be cut short, the amount of families that would be destroyed over the loss of a loved one; these tolls seem almost too much to bear. However, it took just as many people to create the bombs that saved their lives. It is well documented that the United States' economy was resurrected and re-born during the Second World War, and the Manhattan Project was one of the icons of the American home front's immense power during the war. The U.S. government spent $1.89 billion dollars and employed over 485,000 people over the course of the war, which means "approximately 0.4% of all American worked on the bomb project – about one out of every 250 people in the country at the time" (Wellerstein, 2013).
Now, critics may say that Japan's defeat was all but inevitable, and that dropping the atomic bombs was simply an act of genocide aimed at intimidating the Soviet Union and the rest of the world. However, if the bombs were not dropped and the invasion of Japan was allowed to take place – the country of Japan, as well as countless lives would have been destroyed.