The Harbor Defenses of Long Island Sound was a United States Army Coast Artillery Corps harbor defense command. It coordinated the coast defenses of Long Island Sound and Connecticut from 1895 to 1950, beginning with the Endicott program. These included both coast artillery forts and underwater minefields. The area defended included the approach via the Sound to New York City, the port cities and manufacturing centers of New London, New Haven, and Bridgeport, and eventually included the submarine base and shipyard in Groton. The command originated circa 1900 as an Artillery District, was renamed Coast Defenses of Long Island Sound in 1913, and again renamed Harbor Defenses of Long Island Sound in 1925.