Chapter II

THE MARK I. AND MARK IV. TANKS: THE FIRST COMPANIES.

I.

The tank was only just emerging from the primitive stage when the war ended. The Mark V., which entered the field in 1918 (in excellent time for the Amiens retreat), was in the opinion of many people the first tank worthy of the name. But the heat and burden of the day had been borne by the earlier types, whose carcases littered a dozen battlefields all down the line, from the Salient to Cambrai, and whose successes and misfortunes provided the foundation for the final triumph. It will be convenient to deal here with those early types, Marks I. and IV., together, for they differed only in comparatively minor features. Marks II. and III. had no genuine existence. The Mark II. was simply the Mark I. in a slightly advanced stage of evolution without its tail, and the Mark III. was experimental.

Half a chapter on the idiosyncrasies of these machines will not be exciting. It will be difficult even to make it interesting. But such details have to be faced sooner or later, and are better done with for good and all early in the book.

“Big Willie” and its one hundred and fifty Mark I. successors were designed to cope with the conditions encountered on what was then considered to be a typical modern battlefield--namely, that of Loos. On account of its very limited success and disproportionate casualties, this battle won many converts to the theory of the “attack by armour”; but it misled to some extent those who were responsible for specifying the capabilities required of the new weapon. It was not fully realised that by the date when the tanks would be ready for the field, the conditions on most battle-fronts must certainly have changed materially for the worse. Owing to the enormous projected increase in our artillery, the autumn of 1916 was likely to find the terrain immediately behind the enemy’s front line pounded to atoms. But no one foresaw the appallingly destructive effect of such gun-fire as was to blast the Somme and Ypres battlefields during the two ensuing years. It is commonly supposed that the original tank was constructed expressly to meet this difficulty. It was not: it was designed to fight over the moderately shelled areas (as they seem to us now) with which we were familiar at the end of 1915. Actually it made its entry upon ground which, for miles ahead, was convulsed as if by an earthquake, or water-logged like a quagmire; and not until Cambrai did tanks operate under anything approaching favourable conditions.

It was desired to have a machine which, in the first place, would cross a trench nine feet wide. The engineers’ earliest solution embodied huge wheels with caterpillar tracks. But as these wheels, to fulfil the specification, must have had a diameter of fifteen feet, they were ruled out as offering too big a target; and after several intermediate stages, in which varieties of the ordinary tractor model (such as “Mother” and “Little Willie”) were tried and discarded, an ingenious compromise was discovered. In the Mark I. tank (and all later types conformed to this shape) the tracks passed completely round the body of the machine. The underside of this body was in effect a segment of a wheel, as will be apparent to any one who looks at the outline; and the tracks, instead of continuing round the whole periphery, turned back virtually at right angles over the nose and so along the top of the body. The width of trench which could be crossed by machines of this design depended only on their length, or, in other words, on the circumference of the wheel. The Mark I., 26 feet long, could in fact cross an 11-foot gap, climb a vertical obstacle 5 feet high, and crawl up any slope of 1 in 2. Craters, however big, presented no difficulty provided the ground was firm.

On the level the tank was resting on no more than 4 or 5 feet of its length (the wheel again), which gave it when moving a slight fore-and-aft rocking motion. The point of gravity was almost in the centre, and with this admirable balance a skilful driver could lower his machine quite gently down over any drop that was not absolutely sheer. In the Mark I. this operation was facilitated by a cumbersome atrocity known as the hydraulic stabiliser, or, more simply, the tail,--a pivoted structure at the stern carrying two large wheels which was controlled (in theory) by an hydraulic ram. This tail was designed also to assist steering, but when the tank was swung (of which more later) the whole affair had to be raised. It was an abomination from the start; it took anything from five minutes to half an hour to lift; and in action it was the first thing to be disabled or shot away. It was discarded after the Somme battles, where it was found that its loss made little or no difference to the efficiency of the machine, and was, from every other point of view, a godsend.

The tank mounted its main armament in sponsons--a form of projecting gun-casemate borrowed from naval architecture.[3] The male tank carried two Hotchkiss 6-pounder Q.F. naval guns on recoil mountings, protected by close-fitting revolving shields, which gave an arc of fire of about 120 degrees. These are extremely handy little weapons, especially when shortened as in the Mark IV., and could be loaded and fired if necessary by one man. With a calibre of 2¹⁄₄ inches, they fired percussion common shell and case-shot; and although sighted up to 2600 yards, were used normally at quite short ranges, when their enormous flash and detonation, out of all proportion to their size, had a great moral effect. In addition, there was a port in each sponson for a Hotchkiss machine-gun or automatic rifle. The tank commander also was provided with one of these weapons, to be fired (with extreme difficulty) through a port in the cab.

The Mark I. female carried Vickers’ machine-guns, two to a sponson, or four in all, behind revolving shields. The water-jackets were protected by a kind of armoured sleeve, and the gunners sat on bicycle-seats which moved with the shields. The tank commander was again given a Hotchkiss. The Vickers, a beautiful gun, was perfectly satisfactory in a tank; but in the Mark IV., either on account of a shortage of Vickers’ or of some commercial influence, the Lewis gun was introduced as the light weapon throughout both male and female types. As no armoured casing was provided for the barrel, it was disabled very easily by bullets alone, a defect which the Germans did not fail to discover; and in the Mark V. and later types the Hotchkiss (which is all but indestructible) reappeared.

The sponsons of the Mark I. tank were heavy affairs bolted to the side of the machine. The latter then being too wide over-all for carriage by rail, it was necessary before entrainment to unbolt the sponsons and hoist them by a laborious process with a girder and tackle on to specially constructed trolleys, which were towed by the tank. In the Mark IV. an infinitely superior system was substituted. The male sponson, reduced in size and weight, could be pushed inwards, gun and all, after unbolting. On the female tanks a double door, flush with the body, replaced the lower half of the old sponson; the remaining upper half, also more compact than in the Mark I., was bolted down the middle and hinged to the main structure at each end. It was necessary only to unscrew these few bolts and swing the two portions back on their hinges. Although not so simple as they sound, these operations were child’s play in comparison with the earlier abomination of girder and tackle. Moreover, this new arrangement on the female tank had the great advantage of facilitating the entrance or escape of the crew. The manhole in the roof and a dreadful little aperture beside the radiator in the stern were common to both types; but for ordinary use the Mark I. female possessed only a small door, some two feet high, in either sponson; and if the tank were hit and set on fire, some of her men were almost certain to be trapped. With the improved sponson all could escape in a few seconds. Male sponsons, it may be noted, always allow for quite reasonable doors.

So much for the shell and armament of the landship. The motive power was a more difficult problem. There was no time to design and construct special plant: some petrol-driven engine already in use had to be selected. The choice fell eventually on the Daimler 105 H.P. six-cylinder sleeve-valve tractor unit. It must be left to the mechanically-minded to decide whether a more suitable engine could have been discovered. The greatest merit of the Daimler was its comparative simplicity. It was very nearly fool-proof. It took up an immense amount of space, however, for in the Mark I. the differential gear, radiator, and petrol-supply were all enclosed in the body of the tank. There was left just sufficient room for a narrow gangway on either side between the engine and the sponson, for the two seats for the officer and driver in the cab in front, and for further seats on the casing above the crank-shaft and gear-box. Over this casing was the crank-handle for starting up the engine--a process which required normally the efforts of three or four men.

A serious fault existed in the method of transmitting the motive power from the engine to the tracks. Working off the differential, and manipulated by levers, a primitive and infuriating system of secondary gears, pinions, and Coventry chains connected with the sprocket wheels which performed the actual labour of propulsion. Two men were required to work these gears; and no member of any tank crew who took a Mark I. or Mark IV. into action is ever likely to forget the sweat and tears and blasphemy expended over this atrocious system. Apart from the labour and waste of time (and consequent danger) which it involved, it has been asserted by pessimists that 75 per cent of power was lost in the secondary gears and transmission. In addition to changes of speed, these gears played a prominent part in the more frequent act of “swinging.” To alter direction to any appreciable degree the tank had to be swung. The differential was locked, the track on the side toward which the turn was intended was disconnected by putting the secondary gears on that side into neutral, and the other track, with the whole drive behind it, then pulled the tank round--if the soil was firm, virtually on its axis. Handbrakes, working from the officer’s seat to the extension shafts on the differential, assisted in the process, and could be used alone for small changes of direction. Swinging with this transmission was unsatisfactory in the extreme. It required the work of four men, and often was very slow. In the Mark V., epicyclic gears and a one-man control were introduced.

In the Mark I. the petrol-supply was carried in two tanks, one on either side of the cab in front. With this arrangement, whoever else might escape when the machine was set on fire, the officer and driver stood an excellent chance of being burnt alive; and in the Mark IV. an armoured tank holding sixty gallons, placed outside in rear, was substituted. In all types, every available inch of space within was utilised for ammunition racks. The male tank was designed to carry 160 rounds of 6-pounder shell, and 1500 rounds of S.A.A.; the female to carry 7800 rounds of the latter; but, in fact, these numbers were often exceeded, and as much as 27,000 rounds of S.A.A. have been taken into action in a tank. Spare supplies of water, oil, and grease, together with two days’ rations and the crew’s equipment, were tucked away wherever room could be found. It will be apparent, therefore, that there was little scope for movement and no possibility of comfort in a fully-loaded tank. Although ventilation was assisted by a rotary-fan, placed in the stern and worked off the half-time shaft, the heat was terrific: no one could stand upright; and the uproar of the engine was so loud that orders had to be transmitted by signs. Visibility was limited in the extreme. The officer and driver had flaps which, when fully open, gave a fair range of vision immediately in front; but when it was necessary to close these there remained only a number of double glass prisms[4] let into the armour, and some inadequate periscopes thrust up through the roof. After a while naval compasses on gimbals were provided, but in such a mass of steel and iron they proved of very small value.

A few words must be said as to a tank’s method of progression. The two caterpillar tracks, passing completely round the body of the machine, consisted each of ninety hard steel plates with lips for gripping the surface. These tracks did not actually move over the ground; the tank in effect laid its own track, clawed its way along it by means of the two sprocket wheels in the rear, and then picked it up behind and passed it over its head, as it were, before laying it down in front again. During this process the whole weight of the machine rested on a number of flanged rollers, which wore out very rapidly, as did the early sprocket wheels. Tracks and rollers required continual lubrication--the latter by injections from grease-guns. The less said of this ghastly operation the better.

It will be fitting to include in so tedious a section a few statistics. The length of the Mark I. tank was 26 feet 6 inches; its width (including sponsons) 12 feet 9 inches in the male, 10 feet 5 inches in the female; and its height was 8 feet 1 inch. It weighed approximately 26 tons. The armour throughout the body was 12 mm. thick, but on the sponsons, for some obscure reason, only 10 mm. It was proof against shrapnel and ordinary S.A.A., but failed to keep out the “K” armour-piercing bullet which the Germans, apparently on the strength of vague warnings received, had just introduced.

Combinations of the primary and secondary gears gave four different speeds forward and one reverse, the highest reaching something over four miles an hour on level ground. Not more than 30 to 40 yards a minute was expected of a tank across trench systems and heavily shelled areas. The estimated radius of action without a refill was ten hours; and it was not believed that a crew could endure for longer the exhausting conditions amid which they must work and fight. Finally, it was thought that the track-rollers and the sprockets and pinions of the secondary gears would require to be replaced after about fifty hours’ running. As a matter of fact, most of these estimates were conservative. Tanks ran for fifteen hours and more without a refill; their crews withstood the heat and gases for even longer periods; and with improved steel in the sprockets and pinions these were found to survive such journeys as were not dreamed of in the early days.

The Mark IV. was virtually identical with the Mark I. in shape, dimensions, and method of propulsion. Owing to its modified sponsons it was of less width. Its armour was slightly thicker and harder, and kept out the “K” bullets, although the impact of the latter drove splinters from the inside wall.[5] The exhaust, instead of opening direct on to the roof, where its flames often betrayed the position of the tank at night, was led down over the stern. A number of Daimlers of 125 H.P. were mounted in this class, and, with a better type of radiator, raised the speed to about five miles an hour on the level.

In conclusion, we will describe briefly the method of conveying tanks by rail. A 50-ton truck of great length, known officially as a “K.T.,” was designed especially for the purpose; and after a few preliminary rites the tank was driven direct on to this over a ramp. The normal train used in France carried twelve tanks, so that the leader had to drive over eleven trucks before it arrived at its own, the second ten, and so on. The trucks were only four inches wider than the span of the caterpillar tracks: the act of entraining or detraining took place almost invariably at night: occasionally, owing to the faults or exigencies of the railway service, the tanks had to be driven off stern first; and if the line up to the ramp was curved, as often it was, a very nice judgment in driving and guidance was demanded. It often happened that some machine suffering from mechanical trouble required to be towed off by one of its fellows. Finally, at times of great urgency (as for the big concentration before Cambrai), it became necessary to make use of French 30-ton trucks, which were never intended to carry such a load, and were, moreover, actually narrower than a tank. Yet all ranks became so expert in this work that it was not uncommon for an entire company to be entrained in the dark in less than thirty minutes, and detrained in little more. The whole process, with its harrowing contingencies, will fall to be described at a later period in the book; but I may add here that, speaking from memory, I can recall only one serious accident during a move by rail. This happened just before Cambrai, when a tank fell from a French truck as the train was taking a sharp curve. And for that battle some 470 were detrained in a few days in the same area.

II.

In Easter week, 1916, two new companies of the M.G.C., known as the Heavy Section, and lettered “K” and “L,” were formed at Bisley under Lieut.-Colonel Bradley. Colonel Swinton remained at Headquarters in London. The personnel was recruited principally from the A.S.C. (M.T.) and from the classes attested under the Derby scheme. For officers, volunteers for what was described as a new armoured-car unit were gathered in from the ranks of the 18th, 19th, and 21st Royal Fusiliers--the so-called public-school battalions, then in France--and from the Motor Machine Gun Corps. There being as yet no tanks available for training purposes, the programme of work at Bisley was limited virtually to drill and courses in the Hotchkiss guns. It would be absurd to pretend that any of this was taken very seriously. The other established arms of the service, now expanding beyond belief, absorbed all the best regular soldiers left in England; and the new formation suffered inevitably from a lack of competent and energetic senior officers. Many of us must be familiar with the casual methods and discipline which obtained in such embryo organisations in those days, and it is unnecessary to fill in the details. Of the subaltern officers, probably 75 per cent represented as good material as could be found anywhere--a high proportion, in view of the extraordinary and haphazard processes by which the commissioned ranks of the New Army were filled, and one which compared very favourably with that of most infantry units. From the outbreak of war, while the uneducated and unintelligent were obtaining commissions for the asking, there were fighting and dying as private soldiers or N.C.O.’s thousands of men accustomed to responsibility and leadership; and amid this criminal wastage the new corps was lucky to obtain so good a nucleus. As for the original rank and file, they were admirable. A large number, of course, were skilled mechanics; and the fighting qualities of all, under conditions entirely novel and trying in the extreme to nerve and body, were beyond praise.

The prelude at Bisley did not continue long. Arrangements had been made to take over Lord Iveagh’s estate at Thetford, in Norfolk, for training purposes; and the Heavy Section was translated thither in June to make the acquaintance of its new machines. Within the estate the R.E.’s had constructed a model battlefield, with trenches, craters, and other obstacles. Since the enterprise, theoretically, was shrouded in mystery, the whole area was swept clear of inhabitants. Farms and cottages were evacuated. Fences, barbed wire, and sentries kept the East Coast labourer intrigued and amused. Aeroplanes which came too near were fired at. These methods seem, on the whole, to have been successful. It was impossible to conceal the fact that something was doing: beautiful female spies and their less attractive colleagues of the other sex are said to have transmitted vague warnings to the enemy; but until the Mark I.’s appeared on the Somme front the Germans had no definite information to work on. Messrs Foster, building the first 150 at Lincoln, preferred simpler, yet perhaps more subtle, deceptions. There was no secrecy in their yards. Any one could see what they were doing. They were building mobile water tanks for the Russians, those useful people, Russia being notoriously a waterless country and badly served with roads. There are still to be seen a few old training machines which bear inscribed on their sides a legend in large white Russian characters, setting forth their alleged purpose and destination. This last was Petrograd. In such a manner the word “tank” came into use as a convenient code expression, and remained to stay. And as the completed tanks arrived by rail at the training area after dark, it is probable that few persons outside the corps were aware of any connection between the simple Russian water-carriers at Lincoln and the mysterious armoured cars which manœuvred behind the walls of the huge enclosure at Thetford.

On its arrival in the new area the Heavy Section began work in earnest on the machines available. At first, unfortunately, there were not many: there was some delay in delivery, and already there were upwards of a thousand officers and men to be trained. It had been decided to form six fighting companies, of which four were to be ready by the beginning of August. These companies were now lettered from “A” to “F,” and were each to be composed of four sections of six tanks (three male and three female), with one reserve tank, making twenty-five in all. Each section was divided again into three sub-sections of two tanks. A tank crew consisted of a subaltern, three drivers, and four gunners, including an N.C.O. The company was commanded by a major, the sections by captains. The total strength was thirty-one officers and about 200 other ranks. To every two companies there was a quartermaster’s establishment and a workshop’s section of three officers and thirty men. By the 14th August the first four companies--A, B, C, and D--were complete as regards personnel; and the right half of C, with thirteen tanks, had already left for France.

We can prepare to follow. There is no need to enlarge upon the training at Thetford. With the arrival of the actual machines, decorated with Russian characters, interest and zeal revived. It was difficult to remain enthusiastic about the Hotchkiss gun for weeks on end; but to drive a tank across trenches and in and out of craters, even in July, was a novel and piquant form of work. It was felt that things were moving at last: the atmosphere of secrecy was attractive, and there were many indications of the importance already attaching to the new arm. Generals and staff officers came down to witness demonstrations, and the necessary element of humour was provided when a tank-load of them was upset in a trench. The men were both clever and keen, and the most serious trouble was the insufficient supply of machines in which to train them. Many drivers had spent no more than an hour or two in a tank when they left for France. It may well seem, indeed, that the first companies were rushed out too soon; but there were good arguments for the move. The difficulties encountered in the Somme offensive led to a request for the early departure of tanks; and although the training of both officers and men was lamentably incomplete, it was thought that a month or two of actual battle experience would outweigh all the manifest disadvantages of a premature entry. The winter could then be spent in profiting by the lessons learnt. A startling success in the beginning was not anticipated by any one who realised the difficulties to be overcome. The danger rather was of a complete failure, and consequent discouragement; and this possibility had to be faced. It was hoped, however, that the new arm would at least play so good a part as to justify its present claims and its demands for future development.

As we have seen, the right half of C Company left England on the 13th August. The left half followed on the 22nd. D was the next to go, and then A and B. There remained the two later companies, E and F, but these never left the country as units. The other four did all that was asked of them: the experiment was justified; and E and F stayed to form the nucleus of the battalions raised at home when the great expansion of the corps was authorised later in the year.