In 1757, the French general Louis-Joseph de Montcalm conducted a successful siege that forced the British to surrender.

In 1755, Sir William Johnson, British Indian Supervisor of the Northeast, established a military camp at the southern end of Lake George, with the objective of launching an attack on Fort St. Frédéric, a French fort at Crown Point on Lake Champlain.

The French commander, Baron Dieskau, decided to launch a preemptive attack on Johnson's support base at Fort Edward on the Hudson River.

Design and construction of the new fortification was overseen by British military engineer William Eyre of the 44th Foot.

Inside the fort were wooden barracks two stories high, built around the parade ground.

[5] By June the garrison had swollen to about 1,600 men with the arrival of provincial militia companies from Connecticut and New Jersey.

On August 3, 1757, a force commanded by General Louis-Joseph de Montcalm arrived and established camps to the south and the west of the fort.

British Colonel Monro hoped and expected reinforcements from General Daniel Webb, who commanded Fort Edward, 14 miles (23 km) to the south.

Despite Monro's pleas for help sent by messenger, Webb declined to send reinforcements for fear that the large French force would attack Fort Edward next.

The British forces were allowed full honours of war, could keep their colours, muskets with no ammunition, and a single symbolic cannon.

[10] France's Indian allies began plundering the fort almost immediately and killing the sick and wounded British.

Rufus Putnam described the tragedy in his memoirs: "The Indians fell on them, and a most horrid butchery ensued, those who escaped with their lives were stripped almost naked, many in making their escape were lost in the woods where they wandered for several days without food, one man in particular was out ten days and there is reason to believe some perished, in particular the wounded...."[18] In the 1990s, forensic anthropologists excavated human remains at Fort William Henry.

[21] During the production of the 1992 epic war film The Last of the Mohicans, a $1 million copy of Fort William Henry was built on Lake James in western North Carolina.