Fort Lesley J. McNair, on the point of land where the Potomac and Anacostia Rivers join in Washington, D.C., has been an Army post for more than 200 years, third only to West Point and Carlisle Barracks, Pennsylvania, in length of service. The military reservation was established in 1791 on about 28 acres of what then was called Greenleaf Point. Maj. Pierre C. L’Enfant included it in his plans for “Washington, the Federal City,” as a major site for the defense of the capital. An arsenal first occupied the site in 1801; earthen defenses had been there since 1791.

The fortifications did not halt the invading British in 1814. With the British coming overland toward Bladensburg, Maryland, Soldiers at the arsenal evacuated north with as much gunpowder as they could carry, hiding the rest in a well as the Redcoats approached from two directions. About 45 British soldiers were killed and wounded from an accidental explosion when a spark ignited an open barrel of black powder.

“A tremendous explosion ensued,” a doctor at the scene reported, “whereby the officers and about 30 of the men were killed and the rest most shockingly mangled.” The remaining British destroyed the arsenal buildings, but the facilities were rebuilt after the war.

Land was purchased north of the arsenal in 1826 for the first federal penitentiary where the conspirators accused of assassinating President Abraham Lincoln were imprisoned in 1865; after a trial found them guilty, four were executed there by hanging.

Among them was Mary Surratt, the first woman to be executed under federal orders.

The movie “The Conspirator,” recalling these events, came out in 2011.

A hospital was built next to the penitentiary in 1857, and Civil War soldiers who were wounded were treated at what then was called the Washington Arsenal. President Lincoln was a frequent visitor to the arsenal, coming to observe ordnance tests on new weaponry. He also attended the funeral for 21 women war workers who on June 17, 1864, were killed by the explosion of a bin of gunpowder in the room in which they were assembling cartridge cases by hand. A spark ignited fireworks drying outside the building causing the explosion, one of the worst catastrophes to occur in the city of Washington.

The arsenal was closed in 1881, and the post was transferred to the Quartermaster Corps. It was known by the name Washington Barracks. A general hospital was located at the post from 1898 until 1909. Maj. Walter Reed worked there and found the area’s marshlands an excellent site for his research on malaria. The major died of peritonitis after an emergency appendectomy operation at the post in 1902.

The post dispensary now occupies the buildings where Reed worked and died.

About 90 percent of the present buildings on the post’s 100 acres were built, reconstructed or remodeled after 1903.

The post was renamed in 1948 to honor Lt. Gen. Lesley J. McNair, commander of Army Ground Forces during World War II. McNair, who had been headquartered at the post, was killed in Normandy, France, July 25, 1944.