In late June 1775 the Continental Congress, in hopes of adding a fourteenth colony and eliminating a British base for invasion, instructed General Philip Schuyler to take possession of Canada if "practicable" and "not disagreeable to the Canadians." Command of the main wing of the expedition, to march via Ticonderoga to Montreal and down the St. Lawrence, passed to General Richard Montgomery when Schuyler became ill. A second wing led by Colonel Benedict Arnold was to move on Quebec through the wilds of Maine.

Montgomery encountered strong resistance from the British at St. Johns, delaying his assault on Montreal. While undertaking a siege of St. Johns, Montgomery sent Ethan Allen and Major John Brown ahead with separate detachments to recruit Canadian volunteers. Allen and Brown did manage to recruit some Canadians and, meeting together, conceived a risky plan for a converging attack on Montreal by two forces totaling about 300 men. On the night of 24-25 September, Allen with 110 men crossed the St. Lawrence north of the town but was left to fend for himself when Brown failed to meet him. Sir Guy Carleton, British commander, sortied with a force of about 35 Redcoats, 200 volunteers, and a few Indians, and Allen, unable to recross the river, took up a defensive position a few miles from the town.



Most of the Canadian recruits fled when the first shots were fired, but Allen, constantly flanked by the Indians, led his ever-diminishing army on a fighting withdrawal for over a mile. Finally reduced to thirty-one effectives and with a British officer "boldly pressing in the rear," Allen reluctantly surrendered.



On 13 November 1775 Montgomery succeeded in capturing Montreal where Allen's premature attack had failed, but in the end the Canadian expedition was a failure. By June 1776 remnants of the American invasion force, incapable of holding their positions against a reinforced British Army, were back at Ticonderoga.