Keelboat Swivel Gun

A small naval cannon mounted on a swivel in the bow of the keelboat (the 55-foot vessel that carried the expedition up the Missouri River from May 1804 to April 1805). Swivel guns were common naval and frontier fortification weapons, designed to be easily aimed in any direction using a U-shaped yoke mounted on a vertical pin.

The swivel gun served primarily as a deterrent and signaling device, fired during diplomatic encounters and celebrations. It was a key element in the September 25, 1804 confrontation with the Teton Sioux (Lakota), when Lewis ordered it trained on the warriors who were threatening the Corps. When the keelboat returned to St. Louis in April 1805, the swivel gun went with it; it was not carried overland to the Pacific.