On September 17, 1947, James V. Forrestal was sworn in as the first U.S. Secretary of Defense. Previously Secretary of the Navy during World War II, Forrestal left that post to lead the newly established National Military Establishment, the predecessor of today’s Department of Defense. The appointment marked a major postwar reorganization of American military and national-security policy.
Created under the National Security Act of 1947, the National Military Establishment brought the Departments of War and the Navy, along with the newly independent Department of the Air Force, into a common national-security structure. Its purpose was not to erase the services’ separate identities, but to improve strategic coordination, reduce unnecessary duplication, and strengthen civilian direction over the armed forces in the opening years of the Cold War.
Forrestal faced the difficult task of making that new arrangement function amid sharp inter-service rivalries, budget disputes, and growing concerns about Soviet power. He had helped shape the legislation even though he had earlier resisted full military unification, making him an important—and conflicted—figure in the creation of the postwar defense establishment.
The 1947 act also established or formalized several institutions central to modern U.S. national security: the National Security Council, the Central Intelligence Agency, the Department of the Air Force, and the statutory Joint Chiefs of Staff. Forrestal’s role was to begin translating that legislative framework into a working system of civilian-led defense administration.
The office Forrestal held initially led the National Military Establishment, not yet the formal Department of Defense. In 1949, Congress renamed the organization the Department of Defense and expanded the secretary’s authority over the military departments—changes that more fully established the structure recognized today.
Forrestal resigned in March 1949 amid severe physical and mental strain. Despite his brief tenure, his service marked the beginning of the permanent U.S. defense organization that emerged after World War II.
Image: James Forrestal at his desk, via Wikimedia Commons (public domain).
