The battle was to be based on tanks and led by them. There was to be no preliminary artillery bombardment; the day the Tank Corps had prayed for, for nearly a year, was at last fixed, and its success depended on the following three factors:
(i) That the attack was a surprise.
(ii) That the tanks were able to cross the great trenches of the Hindenburg system.
(iii) That the infantry possessed sufficient confidence in the tanks to follow them.
The following difficulties had to be overcome before these requirements could be met. The tanks, on October 20, were scattered over a considerable area: some were at Ypres, others near Lens, and others at Bermicourt. These would all have to be assembled not at suitable entraining stations, as is usually the case, but at various training areas so that co-operative training with the infantry could take place. This was of first importance, for success depended as much on the confidence of the infantry in the tanks as on the surprise of the attack. At these training centres, tanks would have to be completely overhauled and fitted with a special device to assist them in crossing the Hindenburg trenches, which were known, in many places, to be over 12 ft. wide, and the span of the Mark IV machine was only 10 ft. This device consisted in binding together by means of chains some seventy-five ordinary fascines, thus making one tank fascine, a great bundle of brushwood 4½ ft. in diameter and 10 ft. long; this bundle was carried on the nose of the tank and, when a large trench was encountered, was cast into it by pulling a quick release inside the tank. As already described these tank fascines and the “fitments” necessary to fix and release them were made by the Tank Corps Central Workshops.
Before the infantry assembled for training a new tactics had to be devised, not only to meet the conditions which would be encountered but to fit the limitations imposed upon the tank by it being able to carry only one tank fascine. Once this fascine was cast it could not be picked up again without considerable difficulty.
Briefly, the tactics decided on were worked out to meet the following requirements: “To effect a penetration of four systems of trenches in a few hours without any type of artillery preparation.” They were as follows:
Each objective was divided up into tank section attack areas, according to the number of tactical points in the objective, and a separate echelon, or line, of tanks was allotted to each objective. Each section was to consist of three machines—one Advanced Guard tank and two Infantry tanks (also called Main Body tanks); this was agreed to on account of there not being sufficient tanks in France to bring sections up to four machines apiece.
The duty of the Advanced Guard tank was to keep down the enemy’s fire and to protect the Infantry tanks as they led the infantry through the enemy’s wire and over his trenches. The allotment of the infantry to tanks depended on the strength of the objective to be attacked, and the nature of the approaches; their formation was that of sections in single file with a leader to each file. They were organised in three forces: trench clearers to operate with the tanks; trench stops to block the trenches at various points, and trench supports to garrison the captured trench and form an advanced guard to the next echelon of tanks and infantry passing through.
The whole operation was divided into three phases: the Assembly, the Approach, and the Attack. The first was carried out at night time and was a parade drill, the infantry falling in behind the tanks on tape lines, connected with their starting-points by taped routes. The Approach was slow and orderly, the infantry holding themselves in readiness to act on their own initiative. The Attack was regulated so as to economise tank fascines; it was carried out as follows. The Advanced Guard tank went straight forward through the enemy’s wire and, turning to the left, without crossing the trench in front of it, opened right sponson broadsides. The Infantry tanks then made for the same spot: the left-hand one, crossing the wire, approached the trench and cast its fascine, then crossed over the fascine and, turning to the left, worked down the fire trench and round its allotted objective; the second Infantry tank crossed over the fascine of the first and made for the enemy’s support trench, cast its fascine, and, crossing, did likewise. Meanwhile the Advanced Guard tank had swung round, and crossing over the fascines of the two Infantry tanks moved forward with its own fascine still in position. When the two Infantry tanks met they formed up behind the Advanced Guard tank and awaited orders.