The Sullivan Expedition, also known as the Sullivan-Clinton Expedition, is an American campaign led by Major General John Sullivan and Brigadier General James Clinton against Loyalists ("Tories") and the four nations of the Iroquois who have sided with the British in the American Revolutionary War.The expedition occurs during the summer of 1779, beginning June 18 when the army marches from Easton, Pennsylvania, to October 3 when it abandons Fort Sullivan, built at Tioga, to return to New Jersey, and only has one major battle, at Newtown along the Chemung River in western New York, in which about 1,000 Iroquois and Loyalists are decisively defeated by an army of 3,200 Continental soldiers.Sullivan's army then carries out a scorched earth campaign, methodically destroying at least forty Iroquois villages throughout the Finger Lakes region of western New York, to put an end to Iroquois and Loyalist attacks against American settlements as had occurred the previous year.

The devastation creates great hardships for the thousands of Iroquois refugees outside Fort Niagara that winter, and many starve or freeze to death.

The survivors flee to British regions in Canada and the Niagara Falls and Buffalo areas.The Sullivan Expedition devastatee the Iroquois crops and towns and leaves them at the mercy of the British for the harsh winter of 1779-80.

Major Jeremiah Fogg of the 2nd New Hampshire Regiment notes in his journal: "The nests are destroyed, but the birds are still on the wing."

(Eckert, Allan W. (1978).

The Wilderness War, New York: Little Brown & Company).

The expedition objective of ending the frontier war is, however, not realized, as British and Indian attacks will continue in the following years.