His left hand resting on an inexpensive Gideon Bible, Harry S Truman took the presidential oath of office on April 12, 1945. It was an extra 13 days before he received his first substantial briefing on the U.S. effort to develop an atomic weapon--a process fast approaching its climactic stage after more than three years of colossal expense, toil and urgency. Neither Secretary of War Henry Stimson nor Leslie Groves, overseer of the vast atomic project, was in a particular hurry to get the new President's ear because they knew that all the important choices about the Bomb had already been settled. Their conversation with the President on April 25 proceeded accordingly. "Within four months we shall in all probability have completed the most terrifying weapon ever known in human history," Stimson told Truman. The meeting lasted just 45 minutes. None of the men questioned the assumption that the weapon would be used as soon as it was ready, and the sooner the better.
That assumption had animated the creation of the Manhattan Engineering District in the first place. It energized the near manic pace at which Groves ramrodded the project forward. It suffused all thinking about the Bomb's purpose, development and eventual detonation. It was never seriously challenged.
America's atomic project dated from 1939, when Albert Einstein warned Franklin D. Roosevelt that Germany was trying to develop atomic weapons based on an isotope of uranium, U-235. The American nuclear program thus commenced under the sharp prod of fear that Germany would win the race to be the first atomic power. It is fully reasonable to assume that the first U.S. bomb would have been used against Germany had it been available in time.
As it happened, the war in Europe ended before the bomb was built. Stimson appointed the so-called Interim Committee on May 1, 1945, to give advice on the Bomb's use against Japan. Scholars have probed the record of the committee's month-long existence in vain for evidence of the kind of deliberative decision-making process that the resort to nuclear weaponry might seem to have warranted. Stimson asked the committee primarily for recommendations about how, not whether, to use the new weapon. Members spent only about 10 minutes of a lunch break discussing a possible demonstration of the Bomb's effect in an unpopulated area. No other alternatives were brought forward. Without qualifications, the committee recommended "that the bomb should be used against Japan as soon as possible."
The discomforting truth is that Allied leaders strode unhesitantly into the atomic age. "I regarded the bomb as a military weapon and never had any doubt that it should be used," Truman later wrote. "[N]or did I ever hear the slightest suggestion that we should do otherwise," Winston Churchill added. Nothing in the record contradicts them. Dropping the Bomb on Aug. 6, 1945, was among history's most notorious foregone conclusions.