Fort Ticonderoga, formerly Fort Carillon, is a large 18th-century star fort built by the French at a narrows near the south end of Lake Champlain in northern New York. It was constructed between October 1755 and 1757 by French-Canadian military engineer Michel Chartier de Lotbinière, Marquis de Lotbinière during the North American phase of the Seven Years' War, known in the United States as the French and Indian War. The fort was of strategic importance during the 18th-century colonial conflicts between Great Britain and France, and again played an important role during the American Revolutionary War.