During the American Revolutionary War (1775-1783), the Oneidas fought alongside the Continental’s against the British army. Their alliance with the Americans did not fair well with the other Iroquois nations who were sympathetic to the Loyalists and British. Many Iroquois moved north to Canada after the war settling in Ontario and Quebec,
In payment for their assistance during the war, the Treaty of Fort Stanwix in 1784 offered the Oneidas a guarantee of their claim to their traditional homelands. The treaty between the U.S. Continental Congress and the Oneida Nation promised that the Oneidas “shall be secure in the possession of the lands on which they are settled.” This guarantee was again reiterated in the 1789 Treaty of Fort Harmar.
However, between these two Indian treaties the state of New York would force tribal land cessions via the 1785 Treaty at Fort Herkimer and 1788 Treaty of Fort Schuyler. Through these two treaties, the Oneidas would lose most of their ancestral homelands, reducing the Oneida territory from approximately six million original acres to about 300,000 acres. Two years later, the U.S. Congress passed the Indian Trade and Non-Intercourse Act, forbidding purchases of Indian land without prior federal consent. The Treaty of Canandaigua (1794) and the Veterans’ Treaty were signed to protect the boundaries of the occupied Oneida lands. Inspite of this, the state of New York ignored federal efforts to protect the Indian lands. State and local governments would impose a total of 26 treaties and the Oneida territory was further reduced to only a few hundred acres.
In 1822, the Oneida’s purchased rights from the Menominee in the Wisconsin Territory to settle on their lands. By 1838, close to 700 Oneidas relocated to a four-million-acre tract in Wisconsin, which the U.S. federal government would soon reduced to half a million acres. Then, in 1838, the Treaty of Buffalo Creek forced the removal of all Iroquois from New York State while the Wisconsin land base was further reduced to only 65,000 acres near Green Bay. In reaction to the Treaty of Buffalo Creek, some two hundred Oneidas sold their New York land in 1839 and jointly purchased 5,200 acres in Delaware Township near the City of London, Ontario.
During the early 1840s, more than 400 Oneidas moved north into Ontario 240 settling the Oneida Nation of the Thames and others, reuniting with members of the Iroquois Confederacy in Six Nations. It is estimated that about 200 Oneidas remained in New York. Most settling around the town of Oneida, while many moved onto the Onondaga reservation near Syracuse.