Seneca

Seneca is historically the largest of the Six Nations and holds the westernmost position in the Confederacy's image of itself as a single longhouse, giving Seneca, together with Mohawk in the east, the title Keepers of the Doors, and seating Seneca as one of the two Elder Brother nations on the Grand Council. William Fenton's political history of the confederacy assigns Seneca eight chief titles among the fifty the founding five nations divided among themselves, fewer than some smaller nations by strict count but carrying outsized influence in practice as the westernmost check on the Confederacy's diplomacy toward other Indigenous nations and, later, toward colonial New York and Pennsylvania.

Seneca territory in western New York was the last and hardest hit by the 1779 Sullivan Campaign, which burned Seneca towns as thoroughly as it burned Cayuga's, and Seneca land continued to shrink through treaty and purchase across the following two centuries. The Seneca Nation of Indians and the Tonawanda Band of Seneca hold reservations in New York today, and Seneca families also live at Six Nations of the Grand River in Ontario. The Longhouse religion carried by the whole Confederacy was itself reformed by a Seneca prophet, Handsome Lake, in the early nineteenth century, and Seneca communities remain closely identified with the religion's ongoing practice; its medicine societies, including the False Face healing societies shared across the Confederacy, restrict their knowledge to initiated members, and the atlas does not set out their content.

Cornplanter, a Seneca war chief and diplomat of the late eighteenth and early nineteenth centuries, negotiated repeatedly with the young United States and was granted, in return, a personal tract of land along the Allegheny River straddling the Pennsylvania and New York border, one of the few instances of an individual Haudenosaunee leader receiving land in his own name rather than through a nation's treaty. He was a half brother of Handsome Lake, the Seneca prophet who reformed the Longhouse religion, and the two men's shared origin at the village of Ganawagus ties Cornplanter's political career to the religious history his brother made. Thomas Abler's academic biography of Cornplanter is the standard published account of his life and of the grant that carried his name for a century and a half afterward.

In the 1960s the United States Army Corps of Engineers built the Kinzua Dam on the Allegheny River, and the reservoir it created flooded the entire Cornplanter Grant along with roughly ten thousand acres of the Seneca Nation's own Allegany Reservation, despite the 1794 Treaty of Canandaigua's promise that the land would remain Seneca in perpetuity. The flooding destroyed the Cold Spring Longhouse, a spiritual center for traditional Seneca religious practice, and displaced hundreds of Seneca families; in 1964, as the waters rose, engineers relocated Cornplanter's own grave and those of more than three hundred of his descendants and followers from a cemetery about to be submerged. The dam remains, for the Seneca Nation, a documented instance of a federally guaranteed treaty right overridden by a later federal project.