Fort Saint-Jean National Historic Site of Canada

Fort Saint-Jean was designated a national historic site of Canada in 1923 for the following reasons:

• it is associated with the fort built in 1748 by the engineer Chaussegros De Lery under the orders of the Governor, La Galissonnière. At the time, the fort was the rendez-vous for all the military expeditions towards Lake Champlain;
• following its demolition by Commandant de Roquemaure on August 31, 1760, it was rebuilt by Governor Carleton in 1775; and,
• in 1775, it stood a 45 days' siege directed by General Montgomery during the American invasion.

Between 1665 and 1666, the French erected five forts along the Richelieu River to counter Iroquois attacks. The location of the first Fort Saint-Jean, built in 1666 and abandoned in 1672, is unknown to this day. The French used the fort again after the War of the Austrian Succession in 1748, when a new fort was built in Saint-Jean by engineer Gaspard-Joseph Chaussegros de Léry Jr.. The fort comprised a stockade built on piles, 3.5 to 4 metres tall (12 to 13 feet), flanked by bastions at each corner with firing slits for cannons. With the exception of its masonry foundation, all components of the fort were made of wood.

In 1760, the French abandoned and burned the fort, but the surrounding area remained sought after for its strategic location on route to Montreal. In the summer of 1775, during the American Revolution, the fort was once again rebuilt, this time to protect against the cannon fire of the American invasion. Styled after the model by Sébastien Le Prestre, Marquis de Vauban, the new fort withstood a 45-day siege led by the American General Richard Montgomery. Following the 1837 uprising, new fortifications were built on the site, which, since 1952, have formed the core of the Royal Military College Saint-Jean.