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The French classified tanks in three categories:

Chars legers, machines weighing under 10 tons.

Chars mediums, machines weighing 10 to 30 tons, which could be transported by rail on ordinary trucks.

Chars lourds, machines which would require specially constructed trucks for transport by rail.

As the medium tanks were the first constructed and used, their description will be given first. Both the Schneider and St. diamond tanks were smaller and lighter than the British Mark I. or any subsequent pattern of heavy machine, and were, according to British nomenclature, males. The great difference between them and the British heavy tanks was that the designers of the former, in taking the caterpillar tractor as a model, had been content to employ tracks somewhat similarly placed under the body of the machine, and not extending all round it as in the case of the British heavies. The tracks were also shorter

FIG. 9. French Char Schneider.

than the full length of the body, instead of projecting well beyond it, at least at the front, as was the case with the British Whippets, and the French Rcnaults, and both tanks had a particularly " underhung " appearance. It was this arrange- ment of the tracks which militated against the climbing powers of the machines, whilst their comparative shortness limited the spanning powers across a trench.

The Char Schneider (see fig. 9) was 6 metres in length, 2 metres in width and 3-40 metres high. It consisted of an armoured body resting on two horizontal girders with the necessary bracing. The weight was taken by springs on two bogies on each side, which were carried by the track rollers. The track was actuated by a driving sprocket at the rear, there being an idle wheel at the front. The gear- box was at the rear, the radiator in front. Power was given by a four- cylinder Schneider engine of 60 horse-power. The petrol feed was by pressure. Steering was effected by driving the tracks at different speeds. The whole body formed a box of somewhat peculiar shape protected by hardened steel plate of 1 1 -4 mm. thickness on the walls and 5'4 mm. on the roof. There were various openings with movable shutters for observation, etc., and the door was at the back. In front was a steel prow, or beak, to prevent the machine dipping too much when descending into a cavity. The armament consisted of one short 75-mm. gun, of a maximum useful range of 600 metres, mounted on the right cheek of the bows of the machine which could from its position fire only on the right side and not directly ahead. There was also one Hotchkiss machine-gun on each side firing through a spherical shield mounting. For the gun 90 rounds of ammunition were carried and for the machine-guns 4,000 rounds. One officer, one N.C.O., and four men, of whom two were machine- gunners and one a gunner, formed the crew. The officer drove. The total weight of the machine was 13-5 tons and its useful speed from 2 to 4 km. per hour. It could cross trenches of from 1-50 metres to I -80 metres in width, and carried petrol for 6 to 8 hours' work.

The Char St. Chamond (see fig. 10) was a larger and heavier machine. It was 7-91 metres in length, 2-67 metres in width and 2-365 metres or 2-35 high, according to the pattern. It consisted of an armoured body in suitable framework suspended on spiral springs on three bogies on each side, which were carried by the track rollers. The drive was through the rear sprocket. The driving mech- anism was petrol-electric and consisted of a four-cylinder Panhard engine of 80-90 H.P. with electric self-starter, a dynamo of 52 K.W. power and two electromotors, one driving each track. Driving was done by a " tramway " control, by which speed and direction

were regulated. This system had great conveniences, for the machine could be driven from either end without effort, but it had the draw- back of being somewhat complicated and delicate. The petrol feed was by pressure, and the tanks were two superimposed on the left side and one on the right. The whole body formed a box with a square sloping front wjthout any beak. It was enclosed in hardened steel plate of 1 1 mm. thickness in the front shields, and 8-5 mm. at the sides and 5 mm. on top. On the roof there were three observation cylindrical capots with sides of ll-mm. steel above the commander's and driver's ports. The doors were at the sides. The armament con- sisted of one 75-mm. field gun, except in the first 175 machines which had a Special gun, firing ahead in front, and four Hotchkiss machine- guns, one in front to the right of the gun, one on each side and one on the rear face. For the gun 106 rounds of H.E. were carried and for the machine-guns 8,488 rounds of S.A.A. The total weight, loaded, was 24 tons, and its useful speed on the flat 8-5 km. per hour. It could cross trenches up to 2-50 meters in width in good soil. The petrol carried was enough for from 6 to 8 hours. The crew consisted of one officer, one N.C.O., two gunners, four machine-gunners and one mechanic, or nine in all.

During Sept. the first tank of each type arrived at the training centre, where a considerable number of officers and men from different branches of the Service had already collected for pre- liminary individual instruction. An additional training centre for the formation of units was established at Champlicu, and also a depot for the assembly of materiel at Cercottes, near Orleans. It was then decided, also to create the new "Artil- Icrie d'Assaul " and the charter of this organization may be said to date from the 3oth of that month. Col. Estienne was promoted to the rank of general, and was appointed " Comman- dant de I'Arlillcrie d'Assaut aux Armies" and representative of the commander-in-chief in tank matters with the Ministry of Munitions, which department had been created and taken over tank production. In Oct., with the arrival of more machines of both types, the Artillcrie d'Assaut started on its career. It seems that the use of the British tanks at Cambrai, which had been deprecated by the French beforehand, and criticized for the reasons already stated, may have stimulated the French to press on with their own service, though what had been looked upon as the supreme factor of surprise had been discounted.

FIG. 10. French Char St. Chamond.

The work of preparation, including training and equipment, continued throughout the winter, in preparation for the offen- sive to be undertaken in the spring of 1917. On March 31 1917, the organization of the Artillcrie d'Assaut^ was as follows: The tactical unit, under a captain, was the groupe, which was divided into four batteries, each consisting of four tanks. A groupe, therefore, comprised 16 tanks with a special " command " light tank (Renault). For a Schneider tank groupe the estab- lishment was 18 officers and 92 other ranks, for a St. Chamond tank groupe 18 officers and 106 other ranks. A groupement con- sisted normally of four Schneider or three St. Chamond groupes, but was not rigid. For repair work each groupe had its own workshop and a Section de ravitaillemcnt el de reparations

1 Why this arm was ever called " artillery " is not clear. Its closer connexion with, and resemblance to, infantry was recognized later, and the names of the elements of the organization for the light tanks followed those of the infantry, e.g. battalion, company, etc.