In its attack on Fort Chouaguen (Oswego), the French army deployed a large number of troops, including several regiments that arrived in Québec during the spring of 1756. More than 3,000 men, under the command of the Lieutenant-General of the armed forces in New France, Louis-Joseph de Montcalm, his second-in-command, François-Gaston de Lévis, and the Governor General, Pierre de Rigaud de Vaudreuil, were involved in the assault against this English fort, on the southern shore of Lake Ontario. The French tried for 30 years to destroy this trading post, which interfered with their exchanges with the Aboriginal peoples. Two months of preparation and two days of siege resulted in the fall of Fort Chouaguen and the capture of its munitions and food supplies. The English commander James Mercer and 150 of his men were killed; 1,700 were taken prisoner.

Entrée de la rivière Choueguen scituée par les 43 degrés 47 minutes 24 secondes, latitude au sud du lac Ontario avec les plans et élévation de la redoutte que les Anglais ont fait construire en l'année 1727 [Mouth of the Choueguen River situated at 43 degrees 47 minutes 24 seconds latitude south of Lake Ontario with plans and elevation of the redoubt built by the English in the year 1727], by Gaspard-Joseph Chaussegros de Léry, October 8, 1749