Fort Ontario in Oswego NY was the target of a French attack in 1756 during the French and Indian War.
The loss of the Oneida Carry area at Fort Bull in New York State during the French and Indian War in the spring of 1756 meant that the supply lines from Oswego to Fort William Henry were now cut, and left both of these targets vulnerable to further French advances. The French chose to strike at Oswego first.
In 1727, the British had moved into the Oswego area on the shore of Lake Ontario, which had previously been the site of a French trading camp, and built a blockhouse and fort. In 1755, as tensions with the French grew, two more English strongholds, christened Fort George and Fort Ontario, were built nearby. All of them guarded the important port at Oswego, and were manned by 1200 troops from the 50th and 51st Regiments, both of which had been raised in America. At the outbreak of war, Massachusetts Governor William Shirley had prepared to use the area as a jumping-off point for a British assault on Fort Niagara, but those plans were not carried out, partly because the French had naval superiority on Lake Ontario, but mostly because the new British Commander John Campbell Earl of Loudon canceled the idea when he arrived in Albany in July 1756.
Meanwhile, French commander Marquis Louis-Joseph de Montcalm was embroiled in an argument with the Governor General Pierre de Rigaud de Vaudreuil. Montcalm pressed to move troops to Fort Carillon, on Lake Champlain, for an attack against the British at Lake George, while Vaudreuil instead wanted to move against Oswego.
Montcalm, outranked, was forced to give in. He gathered a force of 3,000 men at Fort Frontenac for the attack, including three Regular Army Regiments, some militia, and around 250 Native Americans. A detachment commanded by François-Pierre de Rigaud made their way overland to the British fort, while Montcalm and the rest of the troops landed undetected on the shore of the lake a few miles away.
At dawn on August 10 the British spotted them and opened fire with cannons, but the French made their way up to Fort Ontario and began digging siege trenches. On the afternoon of August 13, the British defenders realized that they could not successfully defend their position, and they withdrew to Fort Oswego. The French now poured in to the abandoned Fort Ontario and set up a number of cannons on the side facing Fort Oswego, and opened fire. At the same time, Rigaud led a small force that was able to approach the opposite side of the British fort. On the afternoon of the 14th, after a cannonball had killed the English commander, the remaining troops inside Fort Oswego surrendered.
It was a smashing victory for Montcalm. The English surrendered 1700 men, and the French and their Native allies celebrated all night with captured British rum. At some point in the night, a group of English prisoners reportedly tried to escape, and the drunken French responded by shooting and tomahawking about 30 of them. It took sometime for Montcalm to restore order and end the massacre.
After ransacking the town for anything useful, Montcalm withdrew back to Fort Frontenac. In his reports, he announced that he had captured “1,600 prisoners, five flags, one hundred guns, three military chests, victuals for two years, six armed sloops, two hundred bateaux and an astonishing booty made by our Canadians and Indians.” The battle was, he declared, “the most brilliant that has ever been fought on this continent.”
The town of Oswego was not reoccupied by the British until 1758, when they used it as a base for operations of their own against Forts Frontenac and Niagara.
Fort Oswego was never rebuilt, and today nothing remains of it. There is a historical marker in the town of Oswego that marks its former position. Fort Ontario was rebuilt by the British in 1759, remained in place for the rest of the War, and then served during the Revolutionary War and was later attacked and wrecked by the British in the War of 1812. Today the ruins make up the Fort Ontario State Historic Site in Oswego.