Conojocular War (1738)
A treaty between Pennsylvania and Maryland ends the Conojocular War with settlement of a boundary dispute and exchange of prisoners.
Background
In the early 18th century, both Pennsylvania and Maryland claimed the same fertile land along what is now the southern Pennsylvania border, each relying on conflicting royal charters. The dispute centered on the area near Conojocular (later Conococheague) Creek, where settlers from both colonies had established homesteads. Maryland maintained that its northern boundary extended above the 40th parallel, which would have included Philadelphia; Pennsylvania insisted its charter placed the border further south. Armed clashes between settlers loyal to each colony began escalating in the mid-1730s, threatening to erupt into full-scale inter-colonial warfare.
Did You Know?
The Conojocular War is considered one of the very few armed conflicts between two British colonial governments in North American history. The border it disputed was not permanently settled until the 1763–1767 Mason-Dixon Line survey, which became the most famous boundary in American history.
The Conflict
Violence intensified in 1736 when Maryland authorities began arresting Pennsylvania settlers in the disputed territory, destroying their crops and homes. Pennsylvania retaliated with its own armed force. The flashpoint was the area around Conojocular Creek, where Thomas Cresap, a Maryland settler who had long been a thorn in Pennsylvania's side, operated a trading post. Penn forces eventually arrested Cresap after a violent confrontation in 1736. Skirmishes continued through 1737 and into 1738, involving armed militias from both colonies facing off over the contested farmland.
Aftermath & Legacy
On May 25, 1738, royal authorities imposed a truce requiring both colonies to release prisoners and cease hostilities while commissioners worked to resolve the boundary. The agreement ended the armed conflict but the border remained formally disputed for decades. It was not until 1763–1767 that surveyors Charles Mason and Jeremiah Dixon drew the definitive line bearing their names, permanently fixing the Maryland–Pennsylvania border. The Mason-Dixon Line later took on broader symbolic significance as the boundary between the free and slave states of the antebellum United States.