He left home, spent time on the western Pennsylvania frontier, and gained the rank of Captain while fighting in the French and Indian War.
He accompanied his father's mission to England, where he studied at Oxford, was admitted to the bar, and acquired strong attachments to the Mother Country.
With his father's help, he was granted the position of Royal Governor of New Jersey, a role he filled from 1763 to 1776. Determined to remain loyal to England, he ws imprisoned, spending two years in harsh confinement.
Released in 1778, he went to the colony of New York, a Loyalist stronghold, where he lived until 1782. When it became evident that the Rebellion was successful, he joined many Loyalists in returning to England. He died there in 1813.
William Franklin and his father were divided by the war, and never reconciled. Like Benjamin Franklin, William had fathered an illegitimate son, whom he had named William Temple Franklin. Benjamin Franklin raised Temple, as he was known, taking him with him to France. Temple served as his grandfather's secretary, conducted correspondence for him, attended meetings, and lived as a young Frenchman for many years. He was completely separated from his father.