 During the evening of 7 August 1944 , the attacking forces formed up in six columns , four vehicles wide , comprising tanks , Kangaroo APCs , half tracks , self @-@ propelled anti @-@ tank guns and Mine flail tanks . At 23 : 00 , Bomber Command commenced the bombardment of German positions along the entire Caen front . At 23 : 30 , the armoured columns began their advance behind a rolling barrage . Movement was slow at first , many APC drivers became disorientated by the dust caused by the vehicles . Several vehicles became stuck in bomb craters . Simonds had arranged several methods for the columns to maintain direction , some vehicles were fitted with radio direction finders , the artillery fired target @-@ marking shells , Bofors 40 mm guns fired bursts of tracer in the direction of advance . In spite of all these measures , there was still confusion . Several vehicles collided or were knocked out . 
