When Montgomery finally began the siege of Fort Saint-Jean, he ordered Allen and about 30 Americans to join with Livingston's Canadians to secure the south bank of the St. Lawrence River against attempts by Carleton in Montreal to relieve the siege [REF].
Allen traveled along the southeastern banks of the Richelieu River, up to Sorel, where he crossed that river and continued up the southern shore of the St. Lawrence to Longueuil.