The Battle of Fort Niagara was a siege late in the French and Indian War, the North American theatre of the Seven Years' War. The British siege of Fort Niagara in July 1759 was part of a campaign to remove French control of the Great Lakes and Ohio Valley regions, making possible a western invasion of the French province of Canada in conjunction with General James Wolfe's invasion to the east.

Fort Niagara, also known as Old Fort Niagara, is a fortification originally built by New France to protect its interests in North America, specifically control of access between the Niagara River and Lake Ontario, the easternmost of the Great Lakes. The fort is on the river's eastern bank at its mouth on Lake Ontario. Youngstown, New York, later developed nearby.