William Harris was born October 7, 1757, on his parents' farm in Willistown Township in the Province of Pennsylvania.
The first known mention of him appears in a memorandum book of Captain Persifor Frazer in the summer of 1776, which calls him a sergeant.
Although records exist showing his involvement in a number of troop movements later in the Revolution, his battalion appears not to have seen any battles in the later years of the war.
[9] Harris was involved in the capture of Joseph Doane, a notorious highwayman and member of a family of robbers, in 1782.
[6] Although a lifetime farmer, Harris was actively involved in community affairs, and was especially interested in public education.
[13] He was also an elder of the Great Valley Presbyterian Church, which his family had joined upon leaving St. Peter's Church in the Great Valley during the Revolution because St. Peter's, an Anglican congregation, continued to say prayers for the King,[14] as was required of Anglican clergy.
John Campbell (1713–1753[17]), a Presbyterian minister, and the former Mary Hubbard (and stepdaughter of Richard Richison[12]), on April 24, 1780.