units had been formed. The elementary system of signalling with flags and with daylight lamps to aeroplanes had been elaborated, pigeons were used, and wireless signalling had been reintroduced, and wireless telephony with aeroplanes had been tried, but not with much success. Intimate cooperation with low-flying aeroplanes had been organized, especially in the direction of noise barrages, machine-gunning and bombing the enemy, chiefly of the hostile guns, and dropping information, as also observation for counter-battery work, and smoke-screens were employed. In short the battle was organized to include and harmonize with the new instrument.
In regard to the future of the tanks, had the war not ended in 1918, certain proposals for expansion for the 1919 campaign, made at the Inter-Allied Tank Committee in Jan. 1918, were again brought up in July, and new establishments for the in- crease of the Tank Corps to a strength of 34 battalions were sanctioned in Oct. This strength, together with the number of some 6,000 machines which it was hoped to produce for 1919, is in itself evidence of the importance attached to the tank arm at the close of the war. Its strength in the field in Oct. 1918 amounted to 12,355 of all ranks, whilst many thousands more were under training at home.
The work of designing and producing the different types of machines which took the field, or were almost ready to do so, necessitated a very large organization. In addition to the Medium Mark A. (Whippet) machines, of which, as has been stated, delivery began in France at the end of 1917, the following types were evolved.
The Mark V. tank (see fig. 8 and table A). This was in design and
size the same as Mark IV., but it was superior to it in the following
particulars: The engine, a 6-cylinder Ricardo engine of 150 H.P.,
was more powerful and was expressly designed for the tank. The
manoeuvring powers were improved by one-man control and an
epicyclic gear. The means of observation were improved. The
unditching gear could be worked from inside the machine. Better
means of clearing the tracks of mud were provided. The design for
this was begun in Oct. 1917 after the experiences of Messines and the
third battle of Ypres, and was to meet the requirements as then
known. Some of these machines reached France in time for the
attack on Hamel on July 4 1918, and this tank was the principal
machine of all the subsequent fighting. In all, 403 were made.
The Mark V. Star tank was the same as a Mark V. machine, with 6 ft. added to the middle of its length. It could cross wider trenches (14 ft.) than the Mark V. machine, and could carry about 20 men in addition to the crew. The design was not started till Feb. 1918, 32 machines being made, of which some were delivered in time for the battle of Amiens. The tank was too long to be very handy.
The Mark V. Two-Star tank was the same as the Mark V. Star, but with a 225-H.P. Ricardo engine. Design was started in May 1918, one being made but not delivered before the Armistice.
The Mark VI. tank was intended to be the same size as the Mark IV. with an improved transmission (the Williams-Janny variable speed gear), but did not get beyond the design stage.
The Mark VII. tank. This was 3 ft. 6 in. longer than the Mark IV. and Mark V. It had a iso-H.P. Ricardo engine and a variable speed gear. Seven were made, but none was used in the field.
The Mark VIII. tank. The design for this machine was commenced in Dec. 1917; seven machines were made, but none was employed in the field. It was larger (34 ft. 2 \ in.) than any other tank, and was designed so as to be made up of parts manufactured in England and the United States, and was to be engined either with the American 300-H.P. Liberty, or the British 3OO-H.P. Rolls-Royce, engine. The engine-room was separated from the fighting-chamber by a bulkhead and the ventilation was improved.
The Mark IX. tank (Infantry tank). The design for this was begun in Sept. 1917. Thirty-five machines were made, but none was actually used. It was a long machine with space in the centre to carry 50 infantry or 10 tons of stores.
The Medium B (Whippet) tank. The design of this, which differed from that of the Medium A, was commenced in June 1917. The shape was more like that of the heavy tanks. It had a four-cylinder I5O-H.P. Ricardo engine. Forty-five machines were made, but none used. In all, 2,636 British tanks were constructed.
The production of the tanks on the first order for 150 which, were in action in 1916, six months after the order had been placed, was, as has been said, a remarkable achievement. After that time supply was carrried out by the Mechanical Warfare Supply Department of the Ministry of Munitions, working in conjunction with the War Office and G.H.Q. in France. The subject was handled by a succession of committees, composed of those concerned, which endeavoured to obtain cooperation and the allocation of responsibility as between the army, which demanded machines and changes of design, etc., and those who had to meet these demands. In Aug. 1918, control was taken over by a Tank Board, to coordinate all sides of the question of supply. There were naturally considerable difficulties in ad- ministration of the production side of this weapon improvised dur- ing hostilities, at a time when the manufacturing resources of the country were already deeply committed in satisfying the
FIG. 8. Mark V. Tank.
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urgent demand for munitions of other kinds. The lack of continuity in the demands, also, which fluctuated as the value of the tank varied in the opinion of the army in the field according to its success in action, made continuity of work and accurate forecasts of output almost impossible. There were also questions of obtaining the necessary labour, manufacturing facilities, raw materials, and that of priority amongst so many competing requirements for carrying on the war. The problem was complicated by the multiplicity of special component parts and fittings required, the great wastage of machines from action in the field, and the quite unexpected wastage by wear and tear of certain parts, some of which, as the design of the machines devcloped, became obsolete before they could be used; and there were the technical difficulties of ensuring efficiency in details, of which the only test could be use in the field.
A great expansion in the sources of supply became necessary as the programmes of construction increased in size, and many engineering firms were engaged in the manufacture of the tanks in addition to the comparatively small number concerned in 1916 and 1917. Before the Armistice the supply of tanks was considered so important that men were relieved from the army to carry on production. The programme for 1919, including Inter-Allied production, which covered over 6,000 machines, required 193,000 tons of steel, 10,000 6-pdr. guns and 30,000 machine-guns, and an expenditure of 80,000,000. By the end
