Fort Trumbull is a massive granite fort near the mouth of the Thames River in New London, Connecticut, managed as Fort Trumbull State Park by the Connecticut Department of Energy and Environmental Protection. The original fort was built in 1777 and named for Governor Jonathan Trumbull. The present fortification was built between 1839 and 1852. It lies adja…Fort Trumbull is a massive granite fort near the mouth of the Thames River in New London, Connecticut, managed as Fort Trumbull State Park by the Connecticut Department of Energy and Environmental Protection. The original fort was built in 1777 and named for Governor Jonathan Trumbull. The present fortification was built between 1839 and 1852. It lies adjacent to the Coast Guard Station New London.