The Germans had recovered from the defeats in the south in July, many defensive positions were out of view of the British artillery and at times poor weather grounded British artillery observation aircraft. The salient at Delville Wood was exposed to German artillery-fire from the north and east and could only be eliminated by an advance at Guillemont, yet of seventy Fourth Army attacks, only twenty were against Guillemont. The attack of was "tactically dubious", despite being a broad front attack co-ordinated with the French. Zero hour was on 23 July but two divisions made zero hour to conform to the French, who then cancelled their attack. The co-ordinated attack planned by the French Sixth Army, Fourth and Reserve armies became uncoordinated minor attacks, at and the first serving to alert the Germans.