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The Department of Defense Celebrates Its 70th Birthday on 10 August 2019

This month we commemorate the 70th anniversary of the founding of the Department of Defense; however, long before the Department of Defense was established, the War Department—created by Congress in 1789—oversaw the fledgling country's Army, Navy, and Marine Corps.

As the nation grew over the next century, the War Department became fragmented and was run by three separate units: the Army Ground Forces, the Army Air Forces, and the Services of Supply. This was extremely inefficient, so in 1947, President Harry Truman signed the National Security Act, forming a unified department known as the National Military Establishment.

The National Security Act created the current position of the Secretary of Defense, but the job was still a subordinate to the preexisting secretaries of the Army, Navy, and Air Force—all still considered cabinet positions.

On 10 August 1949, the National Security Act was amended, making the other secretaries subordinate to the Secretary of Defense, creating the Department of Defense.

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