The HMS St Lawrence was the largest warship ever built on the Great Lakes during the age of sail. During the War of 1812, supply, reinforcement and the movement of troops for attack all depended on the naval control of the lakes. Early in the war the Americans were able to attack York and Fort George with impunity. Because Lake Ontario is effectively landlocked by Niagara in the west and the St Lawrence River rapids in the east, if warships were to operate on the lake, they needed to be built or assembled there.
The size and power of the St Lawrence were a result of the ambition of British naval commodore James Lucas Yeo. He had approval to build a smaller ship, but being far from his commanders in England, he greatly enlarged the ship. The keel was laid on 12 April 1814 at the Point Frederick shipyard in Kingston, Upper Canada. The triple-decker ship of the line was a monster of its time, more powerful even than Lord Nelson's flagship Victory. It eventually carried 112 guns and a crew of 837 officers and seamen, most of whom had to be dispatched from Quebec City. HMS St Lawrence was launched 10 September 1814. In contrast to ocean-going vessels of the time, the ship had a shallow draft and was rather unstable. It was struck by lightning four days after its maiden voyage. Nevertheless, the ship served its purpose. It never saw action because it was such a deterrent.
After the war HMS St Lawrence was decommissioned and its hull used as storage for a local Kingston brewery. Later it was sunk close to shore in Kingston harbour, where it now serves as a popular diving attraction.
See also Ships of the War of 1812.