A blockhouse was a modest fortified building with a distinctive overhanging upper level. In 18th- and 19th-century North America, Britain and the United States built many blockhouses for defence, usually using local materials such as wood because they could be erected relatively quickly and cheaply. This blockhouse was one of three built in St. Andrews to defend the gun batteries that protected the harbour and river, primarily against enemy privateers. Military units stationed here included members of the 104th Regiment of Foot, or New Brunswick Regiment, which is remembered for its 52-day march from Fredericton, New Brunswick, to Kingston, Ontario, in severe winter conditions beginning in mid-February 1813 to reinforce troops there, and later took part in several battles to repel American incursions into Ontario.