Fort Saint-Jean played a crucial role in the British defence strategy during the 1775 American invasion of the Province of Quebec.

In 1663, the French King Louis XIV decided to take direct command of his New France colony, which had been previously colonized and managed by wealthy merchant associations.

[5] Because of bad weather and the weakened state of the few remaining troops, the Americans failed to take Quebec City in their assault on December 31, 1775.

They also built in Saint-Jean an important shipyard to assemble the shallow-draft boats needed to follow the Americans on Lake Champlain.

Known between the wars as Cavalry Barracks, fort Saint-Jean also served as a garrison for a Squadron and a company of The Royal Canadian Regiment.

Initially, only first- and second-year courses were offered and cadets had to complete the remainder of their education at the Royal Military College of Canada (RMC) in Kingston, Ontario.

Over time, the college began offering third- and fourth-year courses and in 1985, it became accredited to grant its own diploma when it received its own Academic Charter.

In order to maintain the CMR site and its buildings in good condition, a non-profit body was created, the Corporation du fort Saint-Jean.

Moreover, the House of Commons' Language School was established in the Massey Building, where many federal Members of Parliament came to improve their French.

However, the site never completely lost its military educational vocation; preparatory-year cadets and groups of officers continued to follow courses at Fort Saint-Jean.

With the years, the museum expanded its collection and new offers several instructive exhibitions about the site's rich military past and history.

The Museum was first located in the Old Guardhouse built by the Royal Engineer between 1883 and 1889, but was relocated in 2005 to the CMR's old Protestant Church to better accommodate its exhibition and customers.

The Musée du Fort Saint Jean has collected some 2,588 pictures for an online photo album illustrative of the history of Collège militaire royal de Saint-Jean from 1952 to 1984.