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.
[Illustration: The Mark V. Tank.]
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.
[Illustration: Disabled Mark II. Tank, Arras, 1917.]
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.