After the French general Marquis de Montcalm staged a heavy bombardment during his seige, the garrison was forced to surrender when relief columns from the south could not break through. Following the surrender to the French on very generous terms, the indian allies began to attack the retreating Engish and Colonial column in order to obtain compensation for their efforts. Many people were killed, captured, or stripped of belongings. They also dug up the graves of people who had died during the seige, infecting themselves and others. The attack was exaggerated in its severity for propaganda purposes. The French burned the fort and retreated to Ticonderoga.

Contrary to popular belief, during the siege most of the soldiers of Fort William Henry were camped outside of the Fort, in the eastern end, and not inside. The fort contained the garrison of regular troops, and the camp contained the Colonial militiamen. Fort William Henry was the staging point for Roger's Rangers.