The siege of St. John's was now pushed on by Montgomery with vigor. Colonel Maclean, with 800 Indians and Canadians, attempted to relieve it, crossing the St. Lawrence in small boats. On nearing the other bank, they were received by so heavy a fire by the Americans posted there that they were obliged to retire without effecting a landing. Provisions and ammunition were now running short in St. John's, there was no hope whatever of relief from the outside, and the officer commanding was therefore obliged to surrender on November 14, after a gallant defense.

As there were only some fifty or sixty regulars in Montreal, General Carleton was unable to defend that town, and, upon the news of the fall of St. John's, he at once retired to Quebec, and Montreal was occupied by the Americans. In the meantime another expedition had been dispatched by the Americans under Arnold. This officer, with 1500 men, had started for Quebec from a point 130 miles north of Boston. Suffering enormous fatigue and hardship, the force made its way up the river; past rapids, cataracts, and through swamps they dragged and carried their boats and stores. They followed the bed of the river up to its source, and then, crossing the watershed, descended the Chaudière and Duloup rivers on to the St. Lawrence, within a few miles of Quebec.