Pitcairn, John (pĭtˈkârn) [key], 1722–75, British royal marine officer in the American Revolution. Major Pitcairn commanded the advance guard of the British troops at Lexington (see Lexington and Concord, battles of) on Apr. 19, 1775, but whether he ordered his men to fire on the colonial militia or was forced to return their fire is still in dispute. He was later killed in the battle of Bunker Hill. Pitcairn Island is named for his son Robert Pitcairn (c.1747–c.1770), who as a midshipman under Philip Carteret first sighted it on July 2, 1767.