mm and 88 mm anti-tank guns was deployed around the villages of Cramesnil and Saint-Aignan-de-Cramesnil behind the German forward positions, to halt any breakthrough by tanks along the Caen–Falaise road. The front line and defences in depth were held by the 89th Infantry Division, 85th Infantry Division (recently arrived from Rouen) and the remnants of the 272nd Grenadier Infantry Division (severely depleted by the Canadians in Operation Atlantic). The 12th SS Panzer Division Hitlerjugend with an attached heavy Tiger tank battalion, with fifty tanks, was in reserve a further back. Some of the infantry were commanded by the German LXXXVI but most of the sector (and the 12th SS Panzer Division) was under the command of the I SS Panzer Corps, which had arrived in the area during Operation Goodwood. Simonds knew that infantry assaults supported by massed artillery had failed to overcome the German forward lines in Operation Atlantic and Operation Spring. During Operation Goodwood, a bombardment by aircraft of RAF Bomber Command had assisted British tanks to break through the German front but they had then suffered many casualties from intact German defences arrayed in depth beyond the bombing. Infantry had been unable to follow up quickly enough to support the leading tanks or to secure ground behind them (follow-up units were also slowed). To solve the tactical problem presented by the terrain and the deep defences, Simonds proposed a radical solution, the first large attack by mechanized infantry. Some field artillery regiments in Canadian and British infantry divisions had been temporarily equipped with M7 Priest 105 mm self-propelled guns for the landings. When they were replaced by towed QF 25-pounder gun-howitzers, these vehicles were superfluous to operations. Simonds had the Priests converted into "Kangaroo" armoured personnel carriers which would allow infantry to follow the tanks closely on any terrain. Permission was first requested from the Americans, from whom the M7s had been borrowed, to convert them into APCs. Simonds made air power fundamental to his plan for breaking through the German defence zones. The preliminary aerial bombardment called for RAF bombers to saturate the German defences on both flanks of a -wide corridor along the axis of the Caen–Falaise road, during the night of 7 August. During the early hours of 8 August, two attacking forces of tanks and armoured personnel carriers would advance along the corridor. West of the road under the 2nd Canadian Division were