Isaac Ingalls Stevens (March 25, 1818 – September 1, 1862) was an American military officer and politician who served as governor of the Territory of Washington from 1853 to 1857, and later as its delegate to the United States House of Representatives. During the American Civil War, he held several Union commands. He was killed at the Battle of Chantilly, while at the head of his men and carrying the fallen colors of one of his regiments against Confederate positions. According to one account, at the hour of his death Stevens was being considered by President Abraham Lincoln for appointment to command the Army of Virginia. He was posthumously advanced to the rank of Major General. Several schools, towns, counties, and lakes are named in his honor.
Descended from early American settlers in New England, Stevens – a man who stood just 5 ft 3 in (1.60 m) tall – overcame a troubled childhood and personal setbacks to graduate at the top of his class at West Point before embarking on a successful military career. He was a controversial and polarizing figure as governor of the Washington Territory, where he was both praised and condemned. He was described by one historian as the subject of more reflection and study than almost the rest of the territory's 19th-century history combined. Stevens' marathon diplomacy with Native American tribes sought to avoid military conflict in Washington; however, when the Yakama War broke out as Native Americans resisted European encroachment, he prosecuted it mercilessly. His decision to rule by martial law, jail judges who opposed him, and raise a de facto personal army led to his conviction for contempt of court, for which he famously pardoned himself, and a rebuke from the President of the United States. Nonetheless, his uncompromising decisiveness in the face of crisis was both applauded by his supporters and noted by historians.
Isaac Stevens was the father of Hazard Stevens, the hero of the Battle of Suffolk and one of the first men to summit Mount Rainier.