William Hepburn was in County Donegal, Ireland in 1753. He migrated to the Thirteen Colonies in 1773 or 1774. Hepburn lived in the Sunbury area for a short time before moving up the West Branch Susquehanna River to what is now Duboistown, where he worked for Andrew Culbertson in digging the race for Culberton's Mill. Hepburn also joined the local militia. During the American Revolution, the West Branch Valley came under attack from Loyalist and Indian forces. These attacks were known as the Big Runaway in 1778 and the later Little Runaway in 1779. Hepburn rose to the position of colonel and was the commanding officer at Fort Muncy, Samuel Wallis's fortified home in Muncy Township. Hepburn, reportedly, gave the orders to Robert Covenhoven and Rachel Silverthorn to spread the word of the impending attacks. Following the Big Runaway, Hepburn kept a permanent connection with the Covenhoven family by marrying Crecy Covenhoven, the sister of Robert. Hepburn also bought of land, to the west of Ross's holdings. His land, known as "Deer Park," when combined with Ross's "Virginia," would eventually become Williamsport.