History of the Department of Defense

The Department of Defense is the cabinet-level executive agency in the federal government of the United States that has authority over all functions relating to the military. With an annual budget approaching $1 trillion, the Department of Defense maintains a civilian workforce of over 700,000 individuals. The number of men and women in the various branches of the armed forces of the United States hovers between 2.1 and 2.5 million people in uniform. The Department of Defense, with its current mission and moniker, came into being on August 10, 1949.

Department of War

The Department of War was the primary predecessor agency of the Department of Defense. The Department of War was established in 1789, very early in the history of the Unites States. What ultimately became the Department of Defense consisted of not only the Department of War, but also the previously independent departments of the Army and Navy, as well as the Air Force when an independent airborne agency was created.

President Truman

President Harry Truman proposed the idea of creating a single cabinet-level department to combine the various agencies in the federal government dedicated to the military. President Truman called his proposed comprehensive agency the Department of National Defense. Announcing his plans in 1945, he encountered stiff opposition from some members of Congress who were opposed to concentrating all of the military authority of the country into one governmental agency.

National Security Act of 1947

After about two years of discussion and debate, the National Security Act of 1947 was passed by Congress and signed into law by President Truman. It was this Act that brought the various military agencies under "one roof" -- into one agency -- for the first time in American history. A single secretary would oversee the operations of the agency and become the principal civilian military leader of the nation, second only to the President in his capacity as Commander in Chief.

National Military Establishment

James V. Forrestal was nominated by President Truman and confirmed by the Senate as the first Secretary of Defense a day after the enactment of the National Security Act of 1947. However, what ultimately would become the Department of Defense did not have that name at that time. Rather, the new agency was officially called the National Military Establishment, or NME. Unfortunately, it took little time for people to realize that when the abbreviated designation of the new agency -- NME -- was spoken, the natural pronunciation was "enemy." In just over two years, in no small part because of this miscue, the agency was renamed the Department of Defense.

The Pentagon

The Pentagon was dedicated and went into use in 1943 as the headquarters for the Department of War and other military agencies. President Franklin Roosevelt took the lead in the construction of this massive structure for the military agencies of the United States. Consequently, since its creation, the Department of Defense has always been located in the Pentagon.