The 1779 Sullivan Expedition, also known as the Sullivan-Clinton Expedition, was an extended systematic military campaign during the American Revolutionary War against Loyalists ("Tories") and the four Amerindian nations of the Iroquois which had sided with the British.
The campaign ordered and organized by George Washington and his staff was conducted chiefly in the lands of the Iroquois Confederacy "taking the war home to the enemy to break their morale", and the expedition was largely successful in that goal as they destroyed more than 40 Iroquois villages and stores of winter crops, breaking the power of the six nations in New York all the way to the Great Lakes, as the terrified Indian families relocated to Canada seeking protection of the British. Today this area is the heartland of New York State, and with the military power of the Iroquois vanquished, the events also opened up the vast Ohio Country, the Great Lakes regions,Western Pennsylvania, West Virginia, and Kentucky to post-war settlements.
Led by Major General John Sullivan and Brigadier General James Clinton, the expedition was conducted during the summer of 1779, beginning June 18 when the army marched from Easton, Pennsylvania, to October 3 when it abandoned Fort Sullivan, built at Tioga, to return to George Washington's main camp in New Jersey. While the campaign had only one major battle, at Newtown (since the tribes evacuated ahead of the large military force) along the Chemung River in western New York, the expedition severely damaged the Iroquois nations' economies by burning their crops, villages, and chattels, thus ruining the Iroquois technological infrastructure. With the Amerindians' shelter gone and food supplies destroyed, thereafter the strength of the Iroquois Confederacy was broken. The death toll from exposure and starvation dwarfed the casualties received in the Battle of Newtown, in which about 1,000 Iroquois and Loyalists were decisively defeated by an army of 3,200 Continental soldiers.