 At 03 : 00 a.m. the mines would be detonated , followed by the attack of nine divisions onto the ridge . The blue line ( first objective ) was to be occupied by zero + 1 : 40 hours followed by a two @-@ hour pause . At zero + 3 : 40 hours the advance to the black line ( second objective ) would begin and consolidation was to start by zero + 5 : 00 hours . Fresh troops from the unengaged brigades of the attacking divisions or from the reserve divisions would then pass through , to attack the Oosttaverne line at zero + 10 : 00 hours . As soon as the black line was captured , all guns were to bombard the Oosttaverne line , conduct counter @-@ battery fire and place a standing barrage beyond the black line . All operational tanks were to join with the 24 held in reserve , to support the infantry advance to the Oosttaverne line . 
