The British made major gains in 1812, as the American army surrendered Detroit and the Indian allies took control of parts of Ohio, Indiana and Illinois, as well as all of Michigan and Wisconsin and points west. In 1813, however, the Americans pushed back and the Indian forces left the southern districts in order to support Tecumseh and the British. The Americans won control of Lake Erie, defeated the British at the Battle of the Thames in Upper Canada, and killed Tecumseh.