With the coming of the American Revolutionary War, American Indians found themselves caught in the middle between the Americans and the British. Many at first tried to stay neutral, but, as the Americans and their ever-growing hunger for land posed the greater existential threat to the native tribes, many (though not all) of them eventually sided with the British, hoping for favorable land concessions at the end of hostilities. In the end, however, things did not go well for the Indians, as seen in the experience of the Iroquois of New York.
The six nations of the formidable Iroquois Confederacy were split during the war, with two of the constituent tribes supporting the Americans and the other four supporting the British. There were divisions within tribes, however: two of the most prominent American Indian leaders in the Revolutionary War, Joseph Brant and Joseph Louis Cook, were both Mohawks, though Brant fought for Great Britain (meeting personally with King George III on a diplomatic mission) and Cook for the Americans (becoming, as a lieutenant colonel, the highest ranking American Indian officer in the Continental Army).
In response to Iroquois raids in the frontier region of western New York, George Washington ordered the Sullivan Expedition in 1779, which destroyed numerous Iroquois villages and drove hundreds of refugees north to Ontario. At the close of the war, the Indian tribes were left out of the peace negotiations of 1783 between the British and Americans, and had to conclude separate agreements with the new American government, in each case ceding yet more of their lands to the European Americans. The Iroquois signed the Treaty of Fort Stanwix in 1784, giving up among other things their claims to the Ohio territory west of Pennsylvania.