In other fronts in North America, Governor of Spanish Louisiana Bernardo Gálvez routed British forces from Louisiana. The Spanish, along with American privateers supplied the 1779 American conquest of Western Quebec (later the US Northwest Territory). Gálvez then expelled British forces from Mobile during the Battle of Fort Charlotte and the siege of Pensacola, cutting off British military aid to their American Indian allies in the interior southeast. Howe's replacement, General Sir Henry Clinton, then mounted a 1778 "Southern strategy" from Charleston. After capturing Savannah, defeats at the Battle of Kings Mountain and the Battle of Cowpens forced Cornwallis to retreat to Yorktown, where his army was besieged by an allied French and American force. An attempt to resupply the garrison was repulsed by the French navy at the Battle of the Chesapeake, and Cornwallis surrendered in October 1781.