In November 1773, William began acquiring land in Northumberland County from J. Cummings. On November 26, 1774 he acquired 180 acres along Mahoning Creek and Susquehanna River known as "Karkaase" from J. Simpson. Following his service in the New York and New Jersey Campaign, William re-settled his family from Chester County to Northumberland. Originally referred to as "Montgomery's Landing", it would become known as Danville after his son, Daniel Montgomery. After developing his farm, William developed the first gristmill, sawmill, and trading post. In 1778, his family fled during the Big Runaway to Fort Augusta and returned following the Battle of Wyoming. In 1792, William constructed the General William Montgomery House. In the same year Daniel plotted the area between Mill Street and Church Street, the historic core of the town.