Following the outbreak of war between the United States and Great Britain in June 1812, Sackets Harbor became the center of American naval and military activity for the upper St. Lawrence Valley and Lake Ontario. The brig Oneida, with a company of marines, was already at the harbor to suppress smuggling between northern New York and Canada. Local woodlands provided ample timber, and a large fleet was constructed at the harbor’s extensive shipyard. Barracks were also built for the thousands of soldiers, sailors, and mechanics who soon arrived to provide the manpower for the invasion and conquest of Canada.
In an attempt to destroy the American shipyard, a British-Canadian force launched an attack on May 29, 1813. At that time the majority of the American forces were across Lake Ontario attacking Fort George. The remaining Americans drove off the enemy, but their narrow victory was marred by a fire that destroyed their military stores. During the remainder of the war, Sackets Harbor was an active station where naval ships were constructed and supplied. In December 1814, the Treaty of Ghent officially ended the War of 1812, and the Lake Ontario fleet was placed in storage at Shiphouse Point.