Located in Washington DC, Fort McNair was established as a military reservation in 1791 on approximately 30 acres of land where the Potomac and Anacostia rivers meet. It was originally intended to be a way to defend the nation's capital. It was taken over by the British in 1814, although they were left a surprise (ammunition in the well) by the US troops who retreated north. The army base was quickly rebuilt after the war. A penitentiary (federal) and hospital were eventually built on land around Fort McNair, which was used very heavily during the US Civil War. The arsenal closed in 1881.
In the early 20th century, the hospital and other buildings on the army base were used to train officers. In 1943, the Army War College was reorganized as the Army-Navy Staff College. In 1976, the National Defense University was formed, consolidating the other colleges on site. In 1948, it became officially known as Fort McNair, named after the famous World War 2 Lt. Gen. Lesley J. McNair. Today, the army base serves as home to the National Defense University, the Commander-in-Chief's Guard, and the US Army's vice chief of staff.