nov 7, 1811 - Battle of Tippecanoe
This battle led to the destruction of the pan-Indian coalition. Before he left to recruit in the south Tecumseh told Tenskwatawa to not engage with the Americans if they approached. But The Prophet had a dream where he was told that God would protect the Native Americans and he attacked William Henry Harrison and the Americans. Harrison's troops won and burned Prophetstown the next day, a devastating blow to all Native Americans and the loss of their best chance to defeat the Americans.
Added to timeline:
Tecumseh's Life Timeline- Trevor Craig