The Battle of Wyoming, also known as the Wyoming Massacre, was a military engagement during the American Revolutionary War between Patriot militia and a force of Loyalist soldiers and Iroquois warriors. The battle took place in the Wyoming Valley of Pennsylvania on July 3, 1778, in what is now Luzerne County. The result was an overwhelming defeat for the Americans. The battle is often referred to as the "Wyoming Massacre" because of the roughly 300 Patriot casualties, many of whom were killed by the Iroquois as they fled the battlefield or after they had been taken prisoner. Concerned that the French might attempt to retake parts of New France they had lost in the French and Indian War, the British military adopted a defensive strategy in Quebec. They recruited Loyalists and enlisted Indian allies to conduct a frontier war along the northern and western borders of the Thirteen Colonies. Colonel John Butler recruited a regiment of Loyalists, while Seneca chiefs Sayenqueraghta and Cornplanter recruited primarily Seneca warriors, and Joseph Brant recruited primarily Mohawks for what became a guerrilla war against the American frontier settlers.

Major Butler with 110 Butler's Rangers and 464 Indigenous warriors departed Tioga Point on June 27, and arrived at the head of the Wyoming Valley three days later. Most of the Indigenous warriors were Seneca and Cayuga led by Sayenqueraghta, Cornplanter, and Fish Carrier, but contingents of Lenape (Delaware), Onondaga, and Tuscarora were also present. The Americans were alerted to their approach when 12 settlers working in a field and nearby tannery were attacked. The battle lasted about 30 minutes. An attempt to reform the American line quickly turned into a frantic rout, as the inexperienced militiamen panicked and ran. It became a deadly race from which only about 60 escaped including Lieutenant Colonel Butler and Colonel Denison. Many of those overtaken by the Seneca and Cayuga were killed and scalped immediately, however, some were taken captive and were later tortured and executed. In his report to the commanding officer of Fort Niagara, Major Butler stated that his Indigenous allies had taken 227 scalps and five prisoners, while Colonel Denison informed him that 302 had been killed. The Seneca Indians were angered from the accusations of atrocities they said they had not committed, and at the militia taking arms after being paroled.