The secretary of war first learned of this work on November 6, 1941 (just a month before Pearl Harbor). “Vannevar Bush came in to convey to me an extremely secret statement,” Stimson wrote in his diary, “a most terrible thing.” (Stimson was the only high-level government figure involved from this point up until the meeting with Truman on April 25, 1945.) The bomb project fell under the command of the United States Army.
