Dieppe raid (1942). First planned in June 1942 but cancelled on 7 July, the Dieppe raid was remounted at the urging of Mountbatten, Chief of Combined Operations, and launched as operation JUBILEE on 19 August. The Germans were aware of the threat of cross-Channel raids and of the assembly of landing craft as early as June, but there is no evidence to support persistent rumours that security was compromised.
The plan called for a frontal assault on Dieppe at 05.20 by 2nd Canadian Infantry Division supported by 58 Churchill tanks. Unfortunately, flank landings at Puys and Pourville timed for half an hour earlier failed to neutralize defences on the two headlands dominating town and seafront. Intelligence, moreover, had missed gun positions in the face of the east headland and anti-armour guns wheeled out after dark at the entrance to streets leading off the esplanade; nor had the immobilizing effect of shingle on tank tracks been anticipated. Consequently, only small parties penetrated Dieppe itself and of the 27 tanks landed only 15 crossed the sea wall. Meanwhile the troops huddled on the beach were at the mercy of 302nd Infantry Division's well-directed fire. Naval and air support was utterly inadequate to resolve this impasse: eight small destroyers and a gunboat lacked the necessary weight of shell, while the RAF's predominantly fighter force was engaged in a major battle of its own.
Of the lessons learnt by JUBILEE, at the cost of 3, 367 Canadian casualties, 106 aircraft, a destroyer, and numerous landing craft, the most valuable was the urgency of providing overwhelming fire support in the initial stage of a landing. Mountbatten's apologists have implied that but for JUBILEE, the Allies would have planned the invasion in 1944 to be dependent on the prompt capture of a major port.
— John P. Campbell
