 Carleton ordered most of the British army to sail upriver toward Sorel on June 9 , but they did not actually leave until he joined them on June 13 . A detachment of 1200 men under Fraser marched up the northern shore toward Berthier and Montreal . The British fleet arrived at Sorel late on the 14th ; the Americans had left there just that morning . Elements of the British army entered Montreal on June 17 , and also arrived at Fort Saint @-@ Jean in time to see the last Americans ( the very last one reported to be Benedict Arnold ) push away from its burning remnants . 
