The capture of Fort Ticonderoga occurred during the American Revolutionary War on May 10, 1775, when a small force of Green Mountain Boys led by Ethan Allen and Colonel Benedict Arnold surprised and captured the fort's small British garrison. The cannons and other armaments at Fort Ticonderoga were later transported to Boston by Colonel Henry Knox in the noble train of artillery and used to fortify Dorchester Heights and break the standoff at the siege of Boston.

Capture of the fort marked the beginning of offensive action taken by the Americans against the British. After seizing Ticonderoga, a small detachment captured the nearby Fort Crown Point on May 11. Seven days later, Arnold and 50 men raided Fort Saint-Jean on the Richelieu River in southern Quebec, seizing military supplies, cannons, and the largest military vessel on Lake Champlain.

Although the scope of this military action was relatively minor, it had significant strategic importance. It impeded communication between northern and southern units of the British Army, and gave the nascent Continental Army a staging ground for the invasion of Quebec later in 1775. It also involved two larger-than-life personalities in Allen and Arnold, each of whom sought to gain as much credit and honor as possible for these events. Most significantly, in an effort led by Henry Knox, artillery from Ticonderoga was dragged across Massachusetts to the heights commanding Boston Harbor, forcing the British to withdraw from that city.