'Stack' was a small British and Canadian undertaking in the Allies' Normandy lodgment to destroy German artillery observation positions in Caen (10/11 July 1944).
On 9 July, after the end of 'Charnwood' in the area to the north of Caen, the Germans reinforced their positions in the city, and in particular Colombelles. General Sir Bernard Montgomery, commander of the 21st Army Group, then ordered the destruction of the tall chimneys of the Société Métallurgique de Normandie factory, whose elevation was being exploited by the Germans as artillery observation positions. This was 'Stack'. whose opposition was provided by army, Waffen-SS and Luftwaffe units: the 32nd Luftwaffen Jägerregiment of Generalmajor Karl Sievers’s 16th Division (L), the 503rd schwere Panzerabteilung, the 2/125th Panzergrenadierregiment of Generalmajor Heinrich-Hermann von Hülsen’s 21st Panzerdivision, and the 54th Werferregiment.
The elements of Lieutenant General Sir Miles Dempsey’s British 2nd Army committed to 'Stack' were the 5/Black Watch, 1/Gordon Highlanders and 5/7th Gordon Highlanders of Brigadier H. Murray’s 153rd Brigade of Major General D. C. Bullen-Smith’s 51st Division, and the 148th Regiment Royal Armoured Corps.
On the night of 10/11 July, the 153rd Brigade launched its attack on positions held by the 503rd schwere Panzerabteilung, the British infantry being supported by the Sherman and Firefly medium tanks of the 148th Royal Armored Corps. The British soldiers were quickly pinned by a rain of mortar bombs and artillery rockets. The PzKpfw VI Tiger II heavy tanks of the III/503rd schwere Panzerabteilung, under the command of Oberleutnant Richard Freiherr von Rose as the unit’s commander, Hauptmann Scherf, was ill, counterattacked at dawn and destroyed nine of the 10 Sherman tanks of 148th RAC’s A Squadron. Three other armoured vehicles were also put out of action and the Germans captured two Sherman tanks: one of these last was later used by the Germans as a tow vehicle. The 153rd Brigade pulled back, losing any chance of achieving the goals of 'Stack'.
Up to that time unaware of the presence of Tiger II tanks in front of them, the British lost 14 Sherman tanks during this engagement. 'Stack' was therefore a failure, and again showed the superiority of German tanks over those of the Allies. It was not until 18 July 18 and 'Atlantic' (the Canadian part of 'Goodwood' [ii]) that the smelter and its chimneys finally fell into the hands of the Allies after the Canadian attack by Briafier K. G. Blackader’s Canadian 8th Brigade (the Queen’s Own Rifles of Canada, the North Shore (New Brunswick) Regiment and Le Régiment de la Chaudière of Brigadier K. G. Blackader’s 8th Brigade of Major General R. F. L. Keller’s Canadian 3rd Division.