“The 3rd and 4th Australian Divisions were ordered to carry out an encircling operation on the night of August 10–11 in order to cut off the Etinehem spur north of the Somme and the ridge east of Proyart, south of the Somme. The general lines of the operation both to the north and the south of the river were similar. Columns were to move along defined roads leaving the objectives well to the flanks, and then encircle the enemy positions. Each column was accompanied by Tanks, and was to move in an easterly direction, and then to wheel inwards towards the Somme. It was recognised that this action involved certain risks, as Tanks had never been tried by night in this way, but in view of the condition of the enemy’s _moral_ at this stage it was considered that the effect of the advance of the Tanks and infantry would lead immediately to the collapse of the defence. “The action north of the river was entirely successful. South of the river the enemy bombed the forward area heavily early in the night, causing considerable delay in the preparations for the attack. Progress was at first slow owing to heavy enemy artillery and machine-gun fire and the disorganisation caused by the bombing. Two of the Tanks allotted for the operations were destroyed or put out of action very soon after zero hour.” Almost from the outset of the attack heavy enemy machine-gun fire was encountered from the large enemy dump by the side of the main road. Tanks were unable in the dark to locate these machine-guns, and could not do much to assist the infantry. It was therefore decided to abandon the operation and withdraw the infantry under cover of unaimed fire from the Tanks, who were themselves recalled when the infantry had got clear away. It was not till the evening of August 12 that Tanks and infantry were able to advance in this sector, and that we gained the positions east of Proyart. By August 11 the Tank Corps reserves were used up, and the Tanks and their crews were almost fought to a standstill. They had had three days of continuous fighting and marching, and of the thirty-eight Tanks which went into action on the 11th there was not one but badly needed overhauling. The crews were completely exhausted. We have already described the conditions under which the men fought in the Mark V. Tank, and how after an average of three hours in a closed Tank whose guns are in action, all men begin to suffer from severe headache and giddiness, and most from sickness, a high temperature and heart disturbance.