When did Tecumseh join forces with great Britain?

Tecumseh, the Shawnee leader, joined forces with Great Britain in the early 1800s, particularly during the War of 1812. His alliance was solidified after the defeat of his brother, Tenskwatawa (the Prophet), at the Battle of Tippecanoe in 1811, which heightened his resolve to resist American expansion. Tecumseh aimed to create a confederation of Native American tribes to oppose U.S. settlers encroaching on their lands, and he saw the British as potential allies in this struggle.