Captain Biddle captured HMS True Briton and three other ships in September 1777, one of his first successes. He had many other victories in his brief career in the Continental Navy.
On March 17, 1778, off Barbados, his ship clashed with HMS Aquila, a British ship captained by Connor Davenport, who was a member of the Hashshashin, rivals of the Templars. Davenport killed Biddle on the lower deck after a duel, and he blew up the ship on Biddle's last requests for the USS Randolph to not be taken as a prize. However, official reports described HMS Yarmouth attacking his ship, and a cannonball to the magazine is what finished Biddle and 305 other crew members.