No single engagement caused greater depression in Germany, but the impression was somewhat fallacious; for behind this sector of the Hindenburg lines were waterways which were even worse obstacles to our tanks, and although the Canadians pressed on to L'Écluse, Écourt, and Rumancourt, they were hemmed in on their left by the Sensée and in front by the Canal du Nord, which protected Douai to the north and Cambrai to the east.