The threat from the west
The Americans had deliberately ignored the British posts on the Great Lakes. They did not have the manpower to capture them, but if Quebec fell, those posts would have to surrender anyway. However, in April Arnold sent Captain Timothy Bedel with 400 men and two guns to fortify a trading post at The Cedars, 40 miles (65km) west of Montreal, to prevent trade and guard against a surprise attack.Captain George Forster, commander of the light company of the 8th Foot based at Oswegatchie, had maintained clandestine links with Montreal and knew of Bedel's mission. The winter had seen the usual Indian migration to his post for handouts, but the warriors had remained longer than usual anticipating action. With 40 Regulars, a dozen British and Canadian volunteers, and 200 warriors under Lorimier, Forster decided to attack Montreal. Leaving on 12 May, he halted at the western shore of Lake Francis, where he learned of Bedel's strength, which demoralized the Indians until a letter arrived from Carleton stating that reinforcements were arriving at Quebec. On 18 May, Forster crossed the lake, headed for The Cedars, and surrounded the stockade.
When Bedel learned of Forster's approach he promptly fell ill, turned over command to Major Isaac Butterfield and fled to Montreal. Lacking artillery, Forster's troops resorted to long-range sniping with the Americans replying in kind. Whilst the firing produced no casualties, the whoops of the warriors created panic inside the stockade. Butterfield was extremely receptive to a summons to surrender, negotiations stalling only when Butterfield insisted that his men retain their arms. As more Canadians arrived to reinforce Forster, Lorimier proposed a simultaneous assault from two sides.
Meanwhile, Arnold had sent Major Henry Sherburn and a further 150 men to reinforce Butterfield and began raising more troops with the intention of following. Sherburn disembarked about nine miles (14km) downstream from The Cedars on the day Forster landed. News of his approach caused Forster to postpone the attack and send some men to watch Sherburn. At this point, Butterfield - unaware that relief was near - offered to surrender if Forster protected his command from the Indians. Forster agreed and the Americans marched out to allow the warriors to plunder the fort. When they had finished, Butterfield and his men returned to their barracks.
