With the development of the steamship, the reefs and rapids of Hell Gate no longer provided natural protection for New York City, and Fort Schuyler and Fort Totten on the opposite shore were built to defend it against attack from Long Island Sound. Fort Schuyler was built between 1833 and 1856, garrisoned during the Civil War, abandoned in 1870, and now houses the State University of New York Maritime College. Its massive granite pentagonal walls, ranging in thickness from five to eleven feet, are pierced by openings for 312 cannon.