George Washington had been pondering plans to strike a blow against the Six Nations. When Congress asked him to act in February 1779, he was ready. Washington proposed a direct and devastating course of action. An army would march into the heart of Iroquois territory. It would see to the “total destruction and devastation” of hostile settlements, many of which were substantial villages surrounded by carefully cultivated fields. The troops were to take as “many prisoners of every age and sex as possible,” to be held as hostages against the good behavior of their warrior sons, fathers, and husbands. Washington did not intend this as a mere raid. He wanted to crush the Six Nations once and for all. He wrote that the lands of the Iroquois were not to be “merely overrun but destroyed.”

Overall command of the operation was given to Major General John Sullivan. He would gather a column of 2,300 men at Easton, Pennsylvania, and then march north through the Wyoming Valley to Tioga. There he would rendezvous with a column of 1,400 Continentals commanded by Brigadier General James Clinton. The united force would then strike north into the enemy's territory.

Logistical problems delayed Sullivan's departure. This frustrated Washington. He had envisioned a swift descent upon the Indians, catching them by surprise. This probably was an unrealistic expectation. Large bodies of Continental troops, unused to the wilderness, were unlikely to catch the Iroquois off their guard. Sullivan and Clinton took no steps to conceal their preparations or presence. Sullivan had to cut a road for his army and its supplies from Easton to Wyoming, not a quiet enterprise. Instead of stealth, Sullivan and Clinton focused on destructive force, bringing along enough troops and artillery to make them more than a match for anything the Iroquois could put in the field.

Sullivan and Clinton joined forces at Tioga on August 22. They had already begun destroying Indian villages along their respective lines of march. On August 26, the combined column moved north. Sullivan took precautions to avoid being ambushed by the Indians. He sent light infantry out in front of his main force and posted strong parties of men to cover his flanks. Essentially invulnerable to Indian attack, Sullivan's advance turned into a military progress through the country of the hostile Iroquois. His men marched in carefully ordered ranks while bands played and drums beat. Sullivan's clear intention was to overawe, demonstrating the inexorable power of the United States. The army took few prisoners, only those who physically could not get out of the way. Most of the Indians fled before the army, the warriors hovering impotently on its fringes.

Town after town went up in smoke. American soldiers wrote in wonder about the fine crops that they were destroying, fruit of the labor of generations of Iroquois women. An officer recorded finding an ear of corn almost two feet long. In addition to fields of crops, the Americans cut down orchards of fruit trees, many of which “appeared to be of great age.” The Butlers and Joseph Brant decided they had to strike a blow against the invaders. They set up an ambush near the Indian settlement of Newtown. On August 29, around 800 loyalists and Indians took station behind a concealed barricade along Sullivan's line of march. The American general's precautions here proved their worth. His scouts detected the barricade, and Sullivan halted his column. He brought up and positioned artillery to bombard the barricade. Perhaps remembering unpleasant lessons from William Howe, Sullivan sent a force around the enemy's left flank. Once he attacked, the loyalists and Indians were swiftly overwhelmed and routed. Casualties were light. Twelve defenders were left dead on the field. The Americans suffered three dead and thirty-nine wounded.

The Battle of Newtown was the only attempt to resist Sullivan. The Butlers and their loyalists, and Brant and his Indians, retreated to Fort Niagara. Sullivan continued his work of devastation until he had burned all but one of the enemy's settlements. He was back at Easton, Pennsylvania, by October 15 and reported to Congress that he had destroyed forty towns and 160,000 bushels of corn.