Final answer:
Prophetstown was destroyed by U.S. forces under the leadership of William Henry Harrison during the Battle of Tippecanoe in 1811. This event significantly weakened the Native American alliance against American expansion.
Step-by-step explanation:
The settlement known as Prophetstown was destroyed in 1811 by U.S. forces led by William Henry Harrison. This attack occurred during the Battle of Tippecanoe, at a time when the population of Prophetstown had swelled to approximately 3,000 Native Americans from various Algonquian tribes. The village was a center for those who followed Tecumseh and Tenskwatawa in their resistance against American expansion. When Harrison's forces confronted Prophetstown, Tecumseh was not present, as he was away building alliances with other native tribes. The ensuing battle saw a defeat for the indigenous forces, and the subsequent burning of Prophetstown by American troops marked a significant turn in the conflict, weakening the Native American alliance against the United States.