When Truman became president on April 12, 1945, upon the death of President Roosevelt, he had no knowledge of the actual bomb project itself and his first information about what was really being done came from Secretary of War Henry L. Stimson on April 25th.
Stimson himself, was virtual head of the project and had been during the years of its development as a military weapon. Stimson had conferred frequently with President Roosevelt during this period but his last meeting with FDR had been on March 15th. (See Stimson biography, "On Active Service." Pg. 615). …
