The Battle of Fort Oswego is one in a series of early French victories in the North American theater of the Seven Years' War won in spite of New France's military vulnerability.

During the week of August 10, 1756, a force of regulars and Canadien militia under General Montcalm captures and occupies the British fortifications at Fort Oswego, located at the site of present-day Oswego, New York.

Montcalm's force seizes the fort's one hundred and twenty-one cannons in addition to seventeen hundred prisoners.

The fall of Fort Oswego effectively interrupts the British presence on Lake Ontario and removes it as a threat to the nearby French-controlled Fort Frontenac.

The battle is notable for demonstrating that traditional European siege tactics are viable in North America when applied properly in the right circumstances and terrain.