Letter from James Forrestal to Representative Clare E. Hoffman of Michigan, June 21, 1947
Disputes over command and control of forces during World War II convinced American military leaders that centralized cooperation between branches of the armed services was essential for future U.S. security. In this letter, Secretary of the Navy James Forrestal, initially opposed to unification, outlined his support for national security legislation. The Senate confirmed Forrestal as the first secretary of defense in September 1947.
Records of the U.S. House of Representatives, National Archives and Records Administration
Only through such a unified organization can we achieve, during time of peace, the balance and common action among our military services with which adequately to meet the challenge of present conditions
The National Security Act
In the aftermath of World War II, Congress passed legislation to modernize the U.S. military and intelligence communities. Known as the National Security Act of 1947, the act merged the Army, Navy, and newly created Air Force into a unified National Military Establishment headed by a secretary of defense. It also created the National Security Council, the Central Intelligence Agency, and the Joint Chiefs of Staff. By approving the act, Congress established an institution to coordinate U.S. defense policy throughout the Cold War era.
The experiences of the war just concluded have proven conclusively that we must maintain in time of peace an adequate organization of the national defense readily available to the needs of war on short notice.
National Security Act of 1947, House Report 80-961, 1947