The operation was conducted Action by Field Marshal Bernard Montgomery 's Anglo-Canadian 21st Army Group , primarily consisting Cause_to_be_included of the First Canadian Army under Lieutenant-General Harry Crerar and the British XXX Corps under Lieutenant-General Brian Horrocks .

Lieutenant-General Brian Horrocks ' XXX Corps ground force advance was delayed Change_event_time by the initial failure of the airborne units to secure bridges at Son en Breugel and Nijmegen .