On 22 February 1767, Arnold married Margaret Mansfield, daughter of Samuel Mansfield, the sheriff of New Haven and a fellow member in the local Masonic Lodge. Their son Benedict was born the following year and was followed by brothers Richard in 1769 and Henry in 1772. Margaret died on 19 June 1775, while Arnold was at Fort Ticonderoga following its capture. She is buried in the crypt of the Center Church on New Haven Green. The household was dominated by Arnold's sister Hannah, even while Margaret was alive. Arnold benefited from his relationship with Mansfield, who became a partner in his business and used his position as sheriff to shield him from creditors.