Fort Steilacoom, founded in 1849 near Lake Steilacoom, was one of the first United States military posts built north of the Columbia River in the region. Established during rising tensions in the Pacific Northwest, it later served as headquarters for the U.S. 9th Infantry Regiment during the conflict often called the Indian War of 1855–56, which grew from Nisqually resistance to the Treaty of Medicine Creek. The fort was also tied to the controversial prosecution of Chief Leschi, whose execution was refused there by the Army before civilian authorities hanged him elsewhere. Decommissioned in 1868, the site later became the nucleus of today’s Western State Hospital.