times. Thirteen of the crew members were killed and 11 were wounded from flying metal fragments. During the Civil War, 56 steamships were built for government service in shipyards on both sides of the Mystic River. After the war, there were dozens of excess war steamships and, after 1870, shipbuilding moved up to Noank within the Groton town limits. One of the largest shipyards was Palmer Shipyard, established in Noank in 1827. A marine railway built in Groton in 1860 allowed them to pull vessels out of the water for repairs, which brought in a lot of business and money. The shipyard was running up to 1913 when one of the Palmer brothers died, but during World War I the shipyard was used again. Iron ships began to be demanded, and their construction attracted workers to Groton. Housing was beginning to run short, so Groton Realty had to hurry to build hotels and cottages. The ships which brought the workers in turn also brought more business to the Realty. The Naval Submarine Base New London was founded in Groton in 1872 as the New London Navy Yard. Submarines were first based there in 1915, and in 1916 it was officially renamed a submarine base. Groton used to include what is now the town of Ledyard, which separated from Groton in 1836. The original center of Groton is still known as Center Groton at the present-day intersection of Route 184 and Route 117, now in the north-central part of town, due to the departure of Ledyard to the north. Groton Center was the location of the town's first school, church, tavern, and stagecoach shop. 20th century In the 20th century, the shipbuilding industry moved from the Mystic River to the Thames River. Electric Boat is the town's largest employer. However, until 1931, submarines designed by Electric Boat were subcontracted to other shipyards, primarily Fore River Shipbuilding in Quincy, Massachusetts. Electric Boat commenced industrial operations in Groton with the establishment of the New London Ship and Engine Company (NELSECO) as a subsidiary in 1911. NELSECO was the primary engine manufacturer for Electric Boat-designed submarines 1911–1925. In 1931, was laid down as the first submarine built in Groton. During World War II, Electric Boat completed submarines every two weeks. In 1954, Electric Boat launched , the world's first nuclear-powered submarine. Presently, Nautilus is decommissioned and open for visitors, permanently berthed at the U.S.