I wouldn't say it was impossible for Barclay to have won the Battle of Lake Erie; certainly, entering the battle he was at a disadvantage, but after two hours of battle, the Lawrence had been so heavily assaulted that it looked as though the British were going to win the battle. This was made possible by Capt. Elliott's reluctance to bring the Niagara into battle until Perry boarded her and brought her in. After the Lawrence was disabled though, the British seamen were for the most part convinced that they might be victorious.
(edit)
