Fort Henry (also known as Fort Henry National Historic Site) is located in Kingston, Ontario, Canada on Point Henry, a strategic point located near the mouth of the Cataraqui River where it flows into the St. Lawrence River, at the upper end of the Thousand Islands. The original fort was constructed during the War of 1812, when present-day Ontario was a British colony known as Upper Canada. The fort was constructed on the high ground of Point Henry to protect the Kingston Royal Naval Dockyard (the site of the present-day Royal Military College of Canada) from a possible United States attack. The fort also monitored maritime traffic on the St. Lawrence River and Lake Ontario, as the loss of this vital shipping route would have cut off supplies to Kingston and the rest of Upper Canada.