The Pennamite–Yankee War (or Yankee-Pennamite Wars) was the intermittent conflict between 1769 and 1799 between settlers from Connecticut, who claimed the land along the North Branch of the Susquehanna River in the present Wyoming Valley, and settlers from Pennsylvania, who claimed the same lands.
Claims on the Wyoming Valley were disputed from the first. The Dutch regarded the Susquehanna River as the border between New Netherland and the English colony of Virginia. King Charles II of England rejected all Dutch claims on North America and, in 1662, granted the land to Connecticut, a full two years before his country's conquest of New Netherland and its subsequent conversion into the Province of New York.
In 1681, Charles II also included the same land in the grant to William Penn. The charter of each colony assigned the territory to the colony; thus, overlapping land claims existed.
In the seventeenth century, fierce resistance by the Susquehannock rendered the debate academic, but by the mid-18th century, the double grant became problematic.
Both colonies purchased the same land by treaties with the Indians. Connecticut sent settlers to the area in 1754. Yankee settlers from Connecticut founded the town of Wilkes-Barre in 1769.
Armed bands of Pennsylvanians (Pennamites) tried without success to expel them in 1769-70, and again in 1775.
The "wars" were not particularly bloody—in the First Pennamite war, two men from Connecticut were killed and one from Pennsylvania in the course of two years.
In 1771, Connecticut's claim was confirmed by King George III.
In 1773, more settlers from Connecticut erected a new town, which they named Westmoreland. However, the Pennsylvanians refused to leave, and, in December 1775, the militia of Northumberland County, Pennsylvania, actually made an abortive attack on a Connecticut settlement.
At the end of the American Revolution, conflicts between the two claimants continued, and in 1782, the Continental Congress overturned the king's ruling and upheld Pennsylvania's claim to the area. But when the state sought to force the Yankees from the land, another Pennamite war ensued, with Connecticut and Vermont sending men to help the settlers.
The controversy ended in 1799, with the Wyoming Valley becoming part of Pennsylvania and the Yankee settlers becoming Pennsylvanians with legal claims to their land