Editor’s Note: Operation “Tractable“ was the second major Canadian operation in Normandy designed to break through the German defensive perimeter to reach Falaise. Like its predecessor, Operation “Totalize,“ “Tractable“ was to employ heavy bombers to augment the firepower available to the troops. The use of heavy bombers in a tactical role was a relatively new tasking for the strategic force and required precise targetting to destroy and disrupt enemy positions. The strategic bomber force, British and American, had made significant contributions to the land battle in Normandy, but there had been mistakes, most notably during Operation “Cobra” when the American 8th Air Force had twice bombed their own troops on 24–25 July causing 136 deaths and an additional 621 casualties. For Operation “Tractable,” the medium bombers of 2 Group, 2nd Tactical Air Force were to bomb German gun, mortar and tank positions along the startline immediately prior to H-Hour. This was to be followed by a large attack by Bomber Command hours after the start of the advance. This bombing was intended “to destroy or neutralize enemy guns, harbours, and defended lacalities on the right flank and to prevent any enemy movement from this area to the area of attack.” (First Canadian Army Op Instruction No. 14, August 1944). Though the air support was largely a success, a number of aircraft mistakenly bombed short hitting units of First Canadian Army. In total, over 150 Allied soldiers were killed and 241 wounded by the short bombing. Though it had little impact on the outcome of “Tractable,” there were a number of investigations launched to understand why the short bombing occurred. The report which follows, dated 25 August 1944 and written by Air Chief Marshal Arthur Harris, Air Officer Commanding-in-Chief of Bomber Command, contains the official RAF post–mortem on the reasons for the accidental bombing of First Canadian Army.