The Battle of St. Louis was an unsuccessful attack led by the British on St. Louis (a French settlement in Spanish Louisiana, founded on the West Bank of the Mississippi River after the 1763 Treaty of Paris) on May 26, 1780, during the American Revolutionary War. A former British militia commander led a force primarily of Indians and attacked the settlement. Fernando de Leyba, the Lieutenant Governor of Spanish Louisiana, led the local militia to fortify the town as best as they could and successfully withstood the attack.

On the opposite bank of the Mississippi, a second simultaneous attack on the nearby former British colonial outpost of Cahokia, occupied by Patriot Virginians, was also repulsed. The retreating Indians destroyed the crops and took captive civilians outside the protected area. The British failed to defend their side of the river and, thus, effectively ended any attempts to gain control of the Mississippi River during the war.