The 1777 Siege of Fort Ticonderoga occurred between the 2nd and 6 July 1777 at Fort Ticonderoga, near the southern end of Lake Champlain in the state of New York. Lieutenant General John Burgoyne's 8,000-man army occupied high ground above the fort, and nearly surrounded the defenses. These movements precipitated the occupying Continental Army, an under-strength force of 3,000 under the command of General Arthur St. Clair, to withdraw from Ticonderoga and the surrounding defenses. Some gunfire was exchanged, and there were some casualties, but there was no formal siege and no pitched battle. Burgoyne's army occupied Fort Ticonderoga and Mount Independence, the extensive fortifications on the Vermont side of the lake, without opposition on 6 July. Advance units pursued the retreating Americans.

The uncontested surrender of Ticonderoga caused an uproar in the American public and in its military circles, as Ticonderoga was widely believed to be virtually impregnable, and a vital point of defense. General St. Clair and his superior, General Philip Schuyler, were vilified by Congress.