April 25, 1945 – Explaining the A-Bomb

On this day in engineering history, President Harry S. Truman learned the full details of the Manhattan Project, a top-secret U.S. government program to build an atomic bomb during World War II. On April 25, 1945, Secretary of War Henry L. Stimson and Army General Leslie R. Groves (photo, right) went to the White House to give the new President an in-depth briefing about the A-bomb. Just ten days earlier, Truman had been sworn in as president when Franklin D. Roosevelt died suddenly. Until then, the former senator from Missouri had known nothing about the super-secret Manhattan Project, a program which Stimson had once prevented him from investigating during a Congressional inquiry into government waste.

On April 24, 1945, Secretary Stimson wrote to Truman to request a meeting "as soon as possible" about "a highly secret matter". The next day, the former lawyer went to the White House with Major General Groves, the military director of the Manhattan Engineer District. A graduate of West Point and long-time member of the Army Corps of Engineers, Groves had overseen the construction of the Pentagon before replacing the Manhattan Project's first director, Colonel James Marshall. Under Groves' able leadership, the slow-paced, poorly-coordinated, theoretical and laboratory research effort of a few universities was transformed into a massive but fast-moving project that involved thousands of engineers, scientists, technicians, and soldiers.

In a memorandum to the President, Stimson began by explaining that "within four months we shall in all probability have completed the most terrible weapon ever known in human history." Although the U.S. enjoyed a near-monopoly on the "great scientific and industrial effort and raw materials" needed to build the A-bomb, the Secretary of War expressed grave concerns about America's future. "It is extremely probable," Stimson noted, that the spread of technology "will make it possible" for an atomic weapon "to be constructed by smaller nations or even groups" for use against a more powerful but "unsuspecting" country such as the United States. For his part, General Groves recommended the creation of a committee of military and scientific advisors to define policies for using atomic weapons in wartime.

That night, President Truman wrote in his diary that "we have discovered the most terrible bomb in the history of the world". Less than three months later, the nuclear age dawned when on July 16, 1945, an atomic bomb was detonated at the Trinity test site in the desert between Alamogordo and Socorro, New Mexico. Later that summer, when President Truman decided to use the A-bomb against Japan, General Groves remarked that "as far as I was concerned, his (Truman's) decision was one of noninterference - basically, a decision not to upset the existing plans."

Resources:

http://www.trumanlibrary.org/whistlestop/study_collections/bomb/large/documents/index.php?documentdate=1945-04-24&documentid=9-14&studycollectionid=&pagenumber=1

http://www.history.com/tdih.do?action=tdihArticleCategory&id=505

http://www.nuclearfiles.org/menu/library/correspondence/stimson-henry/corr_stimson_1945-04-24.htm

http://www.doug-long.com/hst.htm

http://en.wikipedia.org/wiki/Leslie_Groves

http://www.atomicarchive.com/History/mp/p5s2.shtml

http://www.doug-long.com/groves.htm