During the night 18-19 July 1944, 2 Canadian Corps made an assault crossing of the River Orne. This operation was one of the most important of the entire campaign, and its failure would have had a serious effect on the whole operation in Normandy. As part of the Corps plan, 31 Canadian Field Company, the Corps of Royal Canadian Engineers, had the task of constructing a bridge over the River Orne at Caen to allow the passage of the so necessary supporting arms. Failure, therefore, to complete construction of this bridge would have had serious effects on the army plan. Major McCallum was in command of this operation and though harassed by mortar and sniper fire, and by enemy planes, carried on with the task and brought it to a very successful conclusion. His courage, leadership and ability were of the highest order and undoubtedly contributed largely to the success of the operation.