When war broke out between the United States and England in June 1812, Canada again faced the danger of attack from the south, and the Lake Champlain-Richelieu River corridor offered the easiest route toward Montréal, giving Île-aux-Noix major strategic importance. Sir George Prevost, governor-in-chief of British North America, moved quickly as Americans and British competed for naval supremacy on Lake Champlain, and the naval shipyard at Île-aux-Noix expanded rapidly. Construction peaked in the summer of 1814 with the launching of the Confiance, a 12000 ton, 36 gun brigantine, which, though not fully completed, took part in the important naval battle in the Bay of Plattsburgh in September 1814. Captured by the Americans, the vessel lost its anchor and 15 of its cannons, which quickly sank to the bottom of Lake Champlain; one of the anchors, recovered in 1996, is in the entrance hall of Plattsburgh City Hall. Shipbuilding continued during the year after the war, the garrison was gradually reduced throughout the 1820s, and in 1834 the naval shipyard at Île-aux-Noix closed completely. Between 1819 and 1829, the British built a large new stone military fortification with moats and renamed the site Fort Lennox.
