" ‘A Score of Bloody Okinawas and Iwo Jimas’: President Truman and Casualty Estimates for the Invasion of Japan" by D. M. Giangreco, in Pacific Historical Review (Feb. 2003), 487 Cramer Hall, Portland State Univ., Portland, Ore. 97207–0751.

Is an end finally in sight to the controversy over the motivation behind President Harry Truman’s decision to drop an atomic bomb on Hiroshima in August 1945?

Looking back on that fateful decision, Truman said he had been advised that an invasion of Japan might mean up to one million Americans dead or wounded. Revisionist historians have scornfully dismissed that and similar statements as ex post facto rationalizations, unsupported by archival evidence. They charge that Truman’s decision was based on a combination of racism and crass strategic calculation—an assertion that caused a national controversy in 1995 when curators at the Smithsonian Institution’s National Air and Space Museum planned to incorporate it into a special exhibit on the Enola Gay. But a wealth of documentary evidence supporting Truman’s assertion has recently been discovered at the Truman Library in Independence, Missouri, reports Giangreco, an editor at Military Review.

It’s long been known that former president Herbert Hoover wrote a memo for Truman in May 1945, based on secret Pentagon briefings, warning that an invasion could result in 500,000 to one million American deaths. Those figures implied total casualties of two to five million. Historian Barton J. Bernstein has maintained that there’s no proof Truman ever saw the memo.

The newly unearthed documents show that the president not only read the memo, says Giangreco, but "ordered his senior advisers each to prepare a written analysis before coming in to discuss it face to face. None of these civilian advisers batted an eye at the casualty estimate."

At a meeting with the Joint Chiefs of Staff on June 18, Truman heard the participants come at the question another way—by examining the ratios of Americans to Japanese killed in recent operations (1 to 2 for the Okinawa campaign, for example). They used these ratios, Giangreco says, to suggest "how battle casualties from the much larger Japanese and U.S. forces involved in the first of the two lengthy invasion operations on Japanese soil might play out."

Admiral William Leahy, Truman’s chief of staff, said the U.S. casualty rate on Okinawa had been 35 percent, and "that would give a good estimate of the casualties to be expected" in the opening invasion of the southernmost Home Island, Kyushu. None of the others at the meeting disputed Leahy’s view. General George C. Marshall, army chief of staff, reported that 766,700 U.S. troops (not counting replacements for losses) would be needed during the first 45 days of the invasion. With the war then projected to last through 1946, the longer-term implications were clear to Truman and the others present: Unless some means other than invasion were found to end the war, hundreds of thousands of Americans would die.