John Armstrong (1758-1843) was the Secretary of War under President James Madison during the War of 1812. Armstrong served in the Continental Army during the American Revolution. As the Aide-de-Camp of General Horatio Gates he wrote the Newburgh Address, a letter urging officers in the Continental Army to not disband at the end of the war unless grievances regarding back pay and officer pensions were addressed by Congress. After the war, he served in the United States Senate (1801-02, 1803-04), and as United States Minister to France (1804-1810). He was appointed Secretary of War in January 1813.
As Madison's Secretary of War during the War of 1812, he was criticized for his performance. The military failures of the war were not entirely his fault. He had to deal with an undermanned army, an aging officer corps, a small navy, unreliable Congressional funding, and resistance from New England governors unwilling to meet manpower requests. But his own shortcomings compounded these difficulties. Most critically, despite considerable warning, he dismissed all threats of an attack on Washington, D.C., and left the city poorly defended. Heavily criticized by the public, and the president, after the city was captured and burned by British forces, Armstrong resigned on 4 September 1814.