Which British fort was the site of a 1757 massacre?

The British fort that was the site of a 1757 massacre was Fort William Henry.

Built in 1755 at the southern end of Lake George in New York, Fort William Henry guarded an important water route between British New York and French-held Canada. It was named for Prince William Henry, a grandson of King George II, and became a forward base during the French and Indian War.

In August 1757, French forces led by Louis-Joseph de Montcalm besieged the fort. Lieutenant Colonel George Monro surrendered after several days of bombardment, and the garrison was promised safe passage to Fort Edward. During the withdrawal, some Native American allies of the French attacked the departing column, killing and capturing British soldiers, civilians, and camp followers.

The scale and responsibility for the violence remain debated, and early accounts greatly exaggerated the number killed. The episode later became famous through James Fenimore Cooper's novel The Last of the Mohicans. Fort William Henry was destroyed by the French after its capture.