tank could cross trenches up to II ft. 6 in. in width and could climb
a vertical height up to 5 feet. Six of the first establishments of tanks
were equipped with a wireless set capable of sending and also to
some degree of receiving. 1
Two features of the Mark I. tank were not perpetuated in later patterns, except in the first gun-carrier machines. One was the tail. This consisted of a pair of wheels carried by a frame pivoted at the stern of the machine which for ordinary steering could be ac- tuated by the driver by means of wire cables. For sharp turns, which were effected by driving on one track alone, they could be raised off the surface of the ground by a hydraulic ram at the back of the tank. The weight of this tail attachment also served to ease the rate of descent of the tank after crossing a summit, and the extra length it gave to the whole machine increased the width of the gap which could be crossed. It was found in actual practice that the complica- tion and liability to damage the tail was not compensated for by its advantages, and its use was abandoned after the first actions. In both the male and female Mark I. machines the 6-pdr. and Vickers machine-guns were mounted in sponsons to give as far as possible arcs of fire up to direct ahead and astern. In order to reduce the width so that the tanks could be carried by rail these sponsons were removable and could be unshipped for travelling, when they were carried on small wheeled trollies. The inconvenience of this system caused it to be abandoned, and in later patterns of tank the sponsons were so designed that when travelling they could be swung inwards and housed in the width of the tank, or could be unbolted and slid in.
In March 1916, measures were taken to provide the personnel to handle the new weapon, and an establishment was framed for a unit. For secrecy this unit, under the command of Col. Swin- ton, was raised and formed, as a portion of an existing service, under the name of the " Heavy Section," subsequently changed to " Heavy Branch," of the Machine-Gun Corps. This was to provide the personnel for the 150 tanks then under construction, without any reserve of machines or man-power. At first the organization was for three battalions of 50 tanks each, but this was altered to six companies of 25 tanks each, each company consisting of four sections of six tanks and one spare tank. Each section was formed of three male and three female machines, and was subdivided into three sub-sections of one male and one female tank. A specially constructed and equipped mobile field workshop was allotted to each two companies. To assist in the formation of this unit a nucleus of officers and men were transferred from the existing Motor Machine-Gun Corps; officers also being obtained from the cadet battalions, and from France, and other ranks being enlisted from the motor trade. Technical personnel of all ranks was supplied by the Mechanical Transport Branch of the Royal Army Service Corps.
The first headquarters of the Heavy Branch were at Bisley, where, since there were no machines, the training was of a pre- liminary nature confined to discipline and gunnery and the use of the Vickers and Hotchkiss machine-guns. Training in gunnery was carried out by means of borrowed guns, and entailed the sending of the men to Salisbury Plain and to the Naval School of Gunnery at Whale Island. So soon as the tanks began to be delivered from the contractors, the training in driving, tactics and shooting from tanks etc., was carried on in a secret area at Elveden in Suffolk, where a facsimile battlefield had been pre- pared. The whole of this work was carried out under immense difficulties as regards time and the need for secrecy, the main underlying idea of all the preparation being that the role of the unit was to assist and help the infantry. By the beginning of Aug. several machines had been delivered, and a certain amount of training in their use had been carried out.
Meanwhile, the Somme offensive having come to a standstill in spite of the power of the British artillery then available, it was decided to use the tanks, or whatever of them were ready, in the renewal of the attack. Two companies of the heavy branch, 50 tanks with 10 spare machines, were accordingly con- centrated in France for this purpose by the end of Aug., and training was continued preparatory to taking part in operations. Friday, Sept. 1 5, was to mark the appearance of the tank in war- fare, when the secret of the new weapon which had been so carefully kept would be revealed and the weapon itself put to the test. The whole production of the unit up to this time was a remarkable feat. Not only had a number of entirely new
1 This scheme was also abandoned and later found necessary.
machines been manufactured sufficient for 60 to take the field within six months of the order for them having been placed at a time of great industrial stress, but the secret of their creation, which was known to thousands, had been so well kept that they did actually come as a surprise to the enemy.
It was to assist in the further advance of the British right flank, which had begun so successfully at the opening of the battle 10 weeks before, between the Somme and the Ancre that the tanks were to be thrown into the fight. The IV. Army was to break through the enemy's front between the Combles ravine and Martinpuich and seize Morval, Les Boeufs, Gueudecourt and Flers. On its left the Reserve V. Army was to attack and gain Martinpuich and Cource- lette while the French were to press on its right. The cavalry were to ' follow up through the gap which it was hoped would be created and seize the high ground about Rocquigny-Villers au Flos-Riencourt- lez-Bapaume. Two companies of the tanks were engaged, the bulk i with the IV. Army, the rest with the Reserve Army. The general ; idea of their tactics was that they should start so as to reach their ! objectives five minutes before the infantry. They were to act in small detachments of two or three machines against the strong i points in the enemy's defensive system, lanes being left for their advance in the artillery barrage commencing at zero hour.
The tanks advanced at dawn in a slight mist and came as a com- plete surprise to the enemy. The operations, of those with the XV. j Corps of the IV. Army were the most successful; but for various ' reasons the results of the employment of tanks was somewhat dis- I appointing. Of the 49 machines taking part 32 alone reached their i starting points, 9 pushed ahead with the infantry and caused con- siderable loss to the enemy and 9 others, which did not catch up the infantry, did good work in dispersing of the enemy still holding out , at isolated^ spots ; of the balance of 14, 9 broke down and 5 became " ditched." (Ditching was usually caused either by a tank getting ! into such a position in a deep and wide crater or trench that its engine power was not sufficient to pull it out, though the tracks ; gripped, or by weight of the machine being taken by its belly on hard ground, in which case the tracks revolved without biting.) One i tank gave remarkable help to the infantry held up in front of Flcrs by wire and machine-gun fire, when by its action it caused the sur- i render of 300 Germans and enabled the infantry to move on. Another destroyed a field gun. On Sept. 25 and 26, 13 machines acted with the IV. and Reserve Armies. Of these nine were ditched in shell craters, two reached the village of Thiepval and stuck there. But again, as a set-off to mishaps, one single tank on the 26th performed a remark- j able feat which demonstrated the potentialities of the machine. Within one hour, and at the expense of five British casualties, it made possible the capture of a strongly held, well wired, trench (the Gird trench) some 1 ,500 yd. long and strengthened by numerous strong points, which had held up a whole brigade of infantry since the previous evening. The Germans suffered heavy loss, and 8 officers and 362, other ranks, surrendered. On Nov. 15, at the battle of the Ancre after heavy rain, of five tanks that went into action, all became ditched, two machines doing very valuable work before this happened. Next day, in an attack on a field work south of Beau- mont Hamel, one machine out of three employed was put out of ac- tion by shell fire, and two became ditched. The latter, however, were able to bring so effective a fire on the strong point that it sur- rendered and 400 prisoners were collected by the tank crews. But, whatever their defects, the tanks had passed with ease through all entanglements and had destroyed many machine-guns, which weapons, indeed, were practically powerless against it.
The employment of the tanks in Sept. 1916 was contrary to the views of those who had originated the Arm, who were responsible for its production and had most studied its action. They held that the utmost value should be obtained from the new weapon and that the secret of its existence should not be given away until a surprise attack could be carried out on a sufficiently extensive scale to give a chance of achieving a de- cisive success. In this sense the launcl|jng of the tanks was a repetition of the error made by the Germans when they released gas on a small section alone on April 22 1915. Whatever may have been the urgency at that time of reviving the momentum of the Somme offensive, which had died away after weeks of great endeavour and immense sacrifice, and of raising the moral of the tired troops, and whatever might have been the success of the new weapon, it is doubtful if the small number actually employed could have given a result to compensate for the pre- mature disclosure of the secret, which in potential value was equal to that of the 42-cm. howitzers and the poison-gas of the enemy. Again, not only was a small number of tanks used, but they were employed in driblets in different directions, instead of together in as great a mass as their available number would allow. As an experiment this trial of the tanks was, no doubt,
