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.

Widespread looting and burning of buildings occurred throughout the Wyoming Valley subsequent to the battle, but non-combatants were not harmed. Most of the inhabitants fled across the Pocono Mountains to Stroudsburg and Easton or down the Susquehanna River to Sunbury. Within weeks, a widely distributed but highly inaccurate newspaper report claimed that hundreds of women and children had been massacred. This false version of events was accepted as proven fact by many writers for decades afterwards but has been thoroughly discredited.

In 1777, British general John Burgoyne tried to gain control of the Hudson River valley during the American Revolutionary War, but was forced to surrender after the Battles of Saratoga in October. News of the surrender prompted France to enter the war as an American ally. British military officials were concerned that the French might attempt to retake parts of Canada which they had lost in the French and Indian War, so they adopted a more defensive strategy in Quebec.

The British recruited Loyalists and Indigenous allies to conduct a frontier war along the northern and western borders of the Thirteen Colonies. British Indian Department officer John Butler was granted permission to enlist Loyalists in a regiment that came be to known as Butler's Rangers. Seneca chiefs Sayenqueraghta and Cornplanter encouraged Seneca and Cayuga warriors to participate in raids against frontier settlements. Similarly, Mohawk war leader Joseph Brant encouraged Mohawk participation and recruited Loyalist volunteers to fight with him. By April 1778, the Seneca were raiding settlements along the Allegheny River and the West Branch of the Susquehanna River. In late May, Joseph Brant raided Cobleskill in Tryon County, New York.

In early June, Butler, Sayenqueraghta, and Brant met at Tioga Point at the confluence of the Chemung River and the North Branch of the Susquehanna River. Although Butler and the Iroquois were planning a major attack on the Wyoming Valley, it was agreed that Brant would return to Onaquaga and prepare to raid settlements in New York.

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 inhabitants fled to the forts scattered throughout the Wyoming Valley including Fort Wyoming (Wilkes-Barre) and Fort Pittston. Meanwhile, the Patriot militia assembled at Forty Fort under the command of Lieutenant Colonel Zebulon Butler, an officer of the Continental Army home on leave.

On July 1, Fort Wintermoot at the north end of the valley surrendered without a shot being fired. That evening Fort Jenkins also surrendered after a brief skirmish. The terms of the surrender for both forts promised that the inhabitants would not be harmed.