Built before the War of 1812, the Lacolle Blockhouse is one of the last military defense works of its kind still standing in Canada. After the American invasion of 1775 and 1776, British authorities sought better control over access to the Saint Lawrence River through the Richelieu River. In 1778, the Royal Engineers began building a defence network of forts, redoubts, and blockhouses such as the one on the Lacolle River, and Lacolle became an important outpost protecting the entrance to the Richelieu River. On March 30, 1814, American forces under General James Wilkinson attacked British troops entrenched in the Lacolle Mill near the blockhouse, but the American army of 4,000 was routed by 600 British soldiers and Canadian militia, and the fortification was severely tested during the battle. Less than 25 years later, on November 7, 1838, the same site witnessed one of the last confrontations between the Patriotes and loyalist volunteers during the 1837-1838 Rebellion. On November 16, 1960, the Lacolle Mills Blockhouse was classified as a heritage building by the ministère de la Culture et des Communications du Quebec, and in 2007 it was listed on the Canadian Register of Historic Places.
