As settlers moved into the Northwest Territory in increasing numbers, friction with the Native Americans in the area increased. Much of the land was taken from the Indians by force or by deceit. Many resented the influx of settlers, and resistance to settlement increased through the 1780s, especially in the Northwest Territory. In 1791, the Shawnee, under the leadership of Little Turtle, defeated American militia under General Arthur St. Clair. Three years later, however, at the Battle of Fallen Timbers, General Anthony Wayne defeated the Indians of northwest Ohio. In the Treaty of Greenville (1796), Native American leaders gave up Ohio and part of Indiana to the United States, and agreed to leave the area. The federal government signed dozens of treaties with various Native American tribes, generally dealing with land or trade. Between 1795 and 1809, about 48 million acres of Indian land was acquired by the United States. As settlement became more widespread, some Indians began to adopt aspects of Western culture, weakening the importance of their own customs. Many Native American leaders opposed this trend. Seneca Chief Sagoyewatha, called "Red Jacket," was one of the most powerful speakers against Indian assimilation into white culture. Sagoyewatha was particularly concerned about efforts to convert Indians to Christians. In an 1805 speech, he explained to a missionary:
Brother, we do not wish to destroy your religion or take it from you. We only want to enjoy our own ... We will wait a little while and see what effect your preaching has upon [our white neighbors]. If we find it does them good, makes them honest and less disposed to cheat Indians, we will then consider again of what you have said.
Among those who resisted assimilation were two Shawnee leaders: Tecumseh, an orator and Chief of the Shawnee; and Tenskwatawa, his brother, who was called The Prophet. The brothers aimed to unite all Indian nations east of the Mississippi River to resist settlement and return to their own culture and customs. By 1811, the brothers were able to organize a confederation of Indians from the Northwest Territory to Florida. In 1811, while Tecumseh was away from the confederacy headquarters near Tippecanoe Creek, in Indiana; William Henry Harrison led a thousand men against the camp. Although the Battle of Tippecanoe ended as a draw between the two sides, Harrison's forces succeeded in destroying the camp. Settlers saw the battle as a victory, and Indians began to become disillusioned with the confederation. During the War of 1812, Tecumseh and his followers became allies of Britain, fighting against American forces in the Northwest Territory. His efforts were finally ended in 1813, when the Americans defeated the British and their Indian allies at the Battle of the Thames. Tecumseh was killed in the battle, and the confederation disintegrated.