In June 1777, Fort Ticonderoga had been in American hands for two years, but little had been done to strengthen its defenses. The fort, commanded by General Arthur St. Clair, was garrisoned by 2,000 Continental troops but was not prepared to withstand an assault. When the vanguard of British General John Burgoyne’s 7,000-man army arrived in front of Fort Ticonderoga, British officers soon discovered Mount Defiance, a hill that dominated the fort, was unoccupied.

During the American Revolution, Fort Ticonderoga was a strongpoint on the natural waterway between the American colonies and British-controlled Canada. The cannons captured there provided the heavy artillery General Washington needed to intimidate the British out of Boston.