Sullivan had dealt a mighty blow to the prestige of the Iroquois by marching through their lands with impunity. He had also reduced the hostile tribes to penury on the eve of winter. Thousands of Iroquois retreated to the British at Fort Niagara for subsistence. What Sullivan had failed to do was break their will to continue the war.

The Iroquois and the loyalists of John Johnson and the Butlers resumed their attacks in 1780 with renewed fury. They avenged themselves with attacks up and down the frontier. A British force from Canada imitated Sullivan's expedition on a smaller scale by burning the settlements of the Oneida because they had supported the Americans. The Oneida were forced to take refuge with the Americans at Schenectady. The cycle of strategically pointless violence continued into 1781.

The American position in the Mohawk Valley improved when Colonel Marinus Willett, one of the defenders of Fort Stanwix in 1777, was put in charge of its defenses. He fought back energetically and successfully. On October 30, his men routed a party of loyalists and Indians. In this action an Oneida fighting with the Americans shot and killed Walter Butler. Hostilities only ceased on the New York frontier when word arrived that peace negotiations were underway.

The fighting on the frontier was exceptionally brutal, often inflamed by passionate hatred. Both sides committed atrocities. Indian warriors often displayed brutality toward noncombatants and prisoners, despite the efforts of leaders like John Butler and Joseph Brant to exercise some restraint. American fighters often imitated the Indians in taking scalps. In the aftermath of the Battle of Newtown, an American officer skinned the bottom halves of two dead Indians to make pairs of boots for himself and a friend.

The war on the frontier during the American Revolution gravely weakened the Native American peoples. The Cherokee in the south and the Iroquois in the north never recovered their prewar prosperity and power. Even in the Ohio Valley, where the native tribes still remained strong collectively, Native Americans had suffered heavy losses and had not been able to prevent American settlers from firmly entrenching themselves in their midst. Joseph Brant and his people lived in exile in Canada after the war. He tried unsuccessfully to organize a confederacy of all the native peoples of the northwest. The great Shawnee war leader Tecumseh would partially realize this dream before his defeat and death in the War of 1812.