Stimson was American Secretary of War throughout World War II. He had been Hoover’s Secretary of State from 1929-1933 and was appointed to ROOSEVELT’s Cabinet in July 1940 despite being a Republican and already 72 years old. His initial preoccupations were overseeing mobilization and training. Stimson was strongly against America’s isolationist tradition and championed Lend-Lease and increasing aid to Britain. He sought the repeal of the Neutrality Act which would enable merchant ships to be armed and introduced the US’s first compulsory military service in peacetime in 1940. After Pearl Harbor Stimson was in favor of putting Germany first and was especially vocal in advocating the initiation of a ‘second front’ in northwest Europe as soon as possible. However in 1943 he bowed to CHURCHILL’s arguments to postpone Operation Overlord. Stimson attended all the major Allied conferences.
Stimson was also very active in organizing scientific research during the war. In particular he was involved in exploring the possibilities of atomic warfare from a quite early date and was personally responsible for the Manhattan Project. Stimson strongly recommended the use of the Atom bomb in Japan. He resigned in September 1945.