John Armstrong, 1758–1843, American army officer, U.S. Secretary of War (1813–14), b. Carlisle, Pa.; son of John Armstrong, "hero of Kittanning." In the American Revolution he was on the staff of Horatio Gates. In 1783, Armstrong wrote the "Newburgh Addresses," or "Newburgh Letters" ; these anonymously issued appeals urged the restive Continental officers to force Congress to pay salary arrears and adjust other grievances. General Washington denounced the appeals, and the officers soon followed his lead. After marriage (1789) to Alida, sister of Robert R. Livingston, Armstrong moved to Red Hook, N.Y., and became a political supporter of George Clinton and De Witt Clinton. He was U.S. Senator (1800–1802, 1803–4), minister to France (1804–10), and then Secretary of War. In the War of 1812 he was held responsible for the disasters of 1813–14, notably the failure of the expedition to Canada and the British capture of the city of Washington. He resigned in public disfavor. Armstrong wrote Notices of the War of 1812 (1836–40), biographies of Richard Montgomery and Anthony Wayne, and other books.

John Armstrong, 1717?–1795, American pioneer, known as the "hero of Kittanning," b. Co. Fermanagh, Ireland. He laid out the town of Carlisle, Pa. In 1756 he led the expedition that destroyed Kittanning, a town of the Delaware on the Allegheny. Later he was a major general in the American Revolution and a member of the Second Continental Congress.