12. Montgomery decided to use the weather as cover for an assault
On Christmas Day, 1775, Montgomery addressed the troops under his command, informing them of his plans to carry the city by an assault. In consultation with Arnold and Livingston, Montgomery declared his intention to assault the British positions under the cover of a snowstorm, believing it would mask the movement and allow the Americans to use stealth to get over the walls of the town. On the night of December 27, during a brief snowstorm, Montgomery prepared to attack the town, but the storm subsided before the troops could get into position. During the storm, an American deserted the British, and Carleton received the information that the Americans intended to attack during a snowstorm.
After the desertion, Montgomery changed the plan of attack, but continued to rely on the weather to provide cover for the Americans. Diversionary attacks, one led by Livingston, the other by Jacob Brown, were directed against the west side of the British fortifications. Once they were underway two more attacks, led by Montgomery and Arnold, were to strike the Lower Town, with Montgomery attacking the south sector along the Saint Lawrence. Arnold was to advance into the Lower Town from the north. The forces were to join in the Lower Town and jointly attack the Upper Town. Montgomery had been led to believe that once the Americans occupied the Lower Town the residents of the upper would plea with Carleton to surrender. It was a false hope.