Montgomery had led his troops north and occupied Saint Paul's Island in the Saint Lawrence River on November 8, crossing to Pointe-Saint-Charles on the following day, where he had been greeted as a liberator.

Montreal falls without any significant fighting on November 13, as Carleton, deciding that the city is indefensible (and having suffered significant militia desertion upon the news of the fall of St. Johns), withdraws.

He barely escapes capture, as some Americans have crossed the river downstream of the city, and winds prevent his fleet from departing right away.

When his fleet nears Sorel, it is approached by a boat carrying a truce flag.

The boat carries a demand for surrender, claiming that gun batteries downstream will otherwise destroy the convoy.

Based on uncertain knowledge of how real these batteries are, Carleton elects to sneak off the ship, after ordering the dumping of powder and ammunition if surrender is deemed necessary. (There are batteries in place, but not nearly as powerful as those claimed.)