The correct answer is Tecumseh's death. Tecumseh was a prominent Shawnee leader who played a key role in building a confederation of Native American tribes in the early 19th century. However, his death during the Battle of the Thames in 1813 dealt a significant blow to the confederation and ultimately led to its dissolution. The other factors mentioned, such as Canadian losses in York (now Toronto), U.S control of Lake Erie, and U.S victory at the Battle of Horseshoe Bend, may have had some impact but were not the primary cause of the confederation's destruction.
