Fort Ticonderoga played a key role in the history of the United States. Completed in 1755 by the French and named Fort Carillion, the fort's strategic location in the the middle of the Hudson River/Lk Champlain valley made it the focus of whichever army didn't occupy it.
During the French and Indian War, the French used Carillion as a base for attacks on British outposts in the area. In 1758 the British, in an attempt to dislodge the French from the area attacked the fort with 16,000 troops under the command of General Abercrombie. They were repulsed with heavy losses by fewer than 4,000 French defenders.
A year later with the bulk of the fort's garrison redeployed to defend Montreal, the defenders left behind were overmatched by British troops under Sir Jeffrey Amherst and the fort fell. Now under the British, it was re-named Fort Ticonderoga.
Fast forward to the American Revolution and Ticonderoga is still in British hands, though manned with a few dozen troops. In May of 1775 the fort was attacked by a small force of Green Mountain Boys under the command of Ethan Allen and Benedict Arnold. The British surrendered without firing a shot and Arnold secured the fort's cannon, which were moved overland to support the siege of Boston.
By the time the war was in full swing, both the British and Americans felt that the control of the Hudson River Valley was the key to winning the war. Ticonderoga suddenly became important again.
In October of 1776 British troops under the command of Sir Guy Carleton advanced on Ticonderoga. After viewing the formidable defenses, Carleton had second thoughts and retreated to Canada.
A year later a large British force under General Burgoyne moved on Ticonderoga. The Americans, thinking the British would attack Philadelphia, had withdrawn some defenders, making the fort an easier mark. Instead of a frontal assault, Burgoyne wisely settled in for a siege.
Burgoyne noticed that nearby Mt Defiance was left undefended by the Americans. Since Mt Defiance had a commanding view of Ticonderoga, he decided to occupy it. When a subordinate protested that it would be too difficult, Major Phillips responded "Where a goat can go, a man can go; and where a man can go, he can drag a gun"
The American defenders woke up on the morning of July 5th, 1777 to find they were in the line of fire from the cannons Burgoyne stationed on Mt Defiance. Realizing that their position was now untenable,the decision was made to evacuate the fort. In the early morning hours of July 6th,the Americans retreated under the cover of darkness. Fort Ticonderoga was once again in British hands.
In Sept of 1777 the Americans attacked the fort in an attempt to re-take it, but were unable to dislodge the British and retreated.
A month later Burgoyne's northern army was defeated at Saratoga, making Ticonderoga irrelevant. The British held on to it until 1780, then withdrew.
The fort fell into disrepair and was cannibalized by local farmers for stone and building materials. Purchased by a private citizen in 1824, it was restored in 1909 and is now a museum.