The Fort McNair military reservation has been in service for over two centuries. It was established in 1791 as the Washington Arsenal, and renamed after Lieutenant General Lesley McNair in 1948. It was originally established to protect the new city of Washington. When the British invaded in 1814, the arsenal was overwhelmed, overrun, and burned, after the quick removal of powder and mobile equipment, and destruction of immobile equipment.


The Arsenal was rebuilt in the years after. In 1826 the post saw the construction of the first U.S federal penitentiary. This is where, following the Civil War, the conspirators of Lincoln's assassination were tried, found guilty, and hanged. The arsenal was closed in 1881, and transferred to the Quartermaster Corps. During this time, Major Walter Reed, an Army doctor, used the area's marshlands as a site for his research on malaria. As a result, his work helped discover the cause of yellow fever.


During the early 1900's, more changes took place, with most of the post rebuilt. The post became home to the National War College in 1901; and shortly after, the Industrial College of the Armed Forces was established here in 1924. It quickly built a reputation for study of industrial mobilization, as well as a prepping program for officers training to work in high level posts in Army supply organizations. As a mainly training post, most of the rest of Fort McNair's history was quiet, until 1966, when McNair became headquarters for the US Army's Military District of Washington. In 1976, the War College and Industrial College combined to become the National Defense University.


As a result of the BRAC of 2005, Fort McNair joined Fort Myer and Henderson Hall as a joint base. It is the home of the U.S Army Military District of Washington, the Inter-American Defense College, the National Defense University, the US Army Center of Military History, and the 3rd U.S Infantry Regiment.