TWO months before the atomic bomb fell on Hiroshima, President Harry Truman secretly agreed to American war plans that would have launched the largest military invasion in history.
The objective: a full-scale, million-man attack designed to bring Japan to its knees.
While historians still debate the need to drop A-bombs on Japan, there is no argument about one possibility. If the US and Japan had locked in final combat on the empire's home islands, the fighting would have reached levels of ferocity never before seen.
Japanese wartime messages and military documents make clear that the nation's leaders were ready to sacrifice millions of soldiers and civilians, including women and children, in a desperate effort to stave off total defeat. The Japanese strategy was to inflict so many casualties by attacking vulnerable targets like US troop ships that Truman would drop his demand for Japan's unconditional surrender.
''If the invasion had taken place, it would have prolonged the war for over a year, turned Japan into a wasteland, and cost hundreds of thousands of American and Japanese lives,'' says Thomas Allen, co-author with Norman Polmar of ''Code-Name Downfall'' [Simon & Schuster, 1995], a just-published history of the final days of World War II in the Pacific. ''It would have been the bloodiest and fiercest battle in history.''
''Imagine the German casualties that would have resulted from an invasion of England, and you get an idea of how fierce the defense of the Japanese homeland would have been,'' Mr. Allen elaborates.
In preparation for a final assault on Japan, Truman ordered up 1 million soldiers, sailors, and marines, many redeployed from Europe, where the war against Germany had already been won.
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