 Operation Tractable incorporated lessons learned from Operation Totalize , notably the effectiveness of mechanized infantry units and tactical bombing raids by heavy bombers . Unlike the previous operation , Tractable was launched in daylight . An initial bombing raid was to weaken German defences and was to be followed by an advance by the Canadian 4th Armoured Division on the western flank of Hill 195 , while the Canadian 3rd Infantry Division attacked on the eastern flank with the Canadian 2nd Armoured Brigade in support . Their advance would be protected by a large smokescreen laid down by Canadian artillery . Field Marshal Bernard Montgomery hoped that Canadian forces would achieve control of Falaise by midnight on August 14 . From there , all three formations would advance towards Trun , 18 kilometres ( 11 mi ) east of Falaise , with the additional assistance of the Polish 1st Armoured Division , numbering approximately 10 @,@ 000 men . Once in Trun , a linkup with the American 3rd Army at Chambois could be quickly accomplished . 
