The First Canadian Army executed Operation Veritable in difficult conditions from Nijmegen eastwards through the Reichswald Forest then southwards. This was to have been the northern part of a pincer movement with the US Ninth Army moving northwards towards Düsseldorf and Krefeld (Operation Grenade), to clear the west bank of the Rhine north of Cologne. However the Americans were delayed by two weeks when the Germans destroyed the Roer dams and flooded the American route of advance. As a result, the Canadians engaged and mauled the German reserves intended to defend the Cologne Plain.