Cherbourg Harbour has been a strategic position during centuries of European warfare. Cited as one of the "keys to the kingdom" by 17th-century Marshal Sebastien Vauban, it became a first-rate military port under the leadership of Louis XVI and Napoleon Bonaparte, and holds an arsenal of the French Navy. In 1864, during the American Civil War, the CSS Alabama encountered the USS Kearsarge at Cherbourg Harbor, and the Alabama was sunk in the confrontation. On 10 April 1912, the RMS Titanic docked in Cherbourg as its penultimate port of call. Cherbourg was the primary goal of U.S. troops during the invasion of Normandy in 1944.