II
The First Battle of Cambrai was to be a single-minded battle. It was to fulfil in the simplest way the prime function of war, that is, to destroy the forces of the enemy.
To attain this end it was to rely upon surprise, audacity, and rapidity of movement.
Its main action was to be completed in about twenty-four hours, during which time it was proposed to penetrate the Hindenburg Line, which here consisted of four systems of trenches. Territorial gains were not to be so much considered as were the destruction and capture of enemy personnel and material. In other words, we were out to kill and chivvy Germans. The system of attack was to be one completely new for a full-dress battle. There was to be no artillery preparation whatever. To all appearance the front line was to be perfectly normal up to the very moment of attack, when two Army Corps and three Brigades of Tanks were suddenly to hurl their whole weight against the enemy.
Such tactics demanded that the most complete secrecy should be maintained up to zero hour itself, and for the second time in the history of the Tanks a vital secret was successfully kept.
The area to be raided lay just south of Cambrai. It was an open rolling chalk plateau, which had lain uncultivated for two years, and was now covered with a thin growth of wan grey grass.
From north-west to south-east the low ridges ran, save where the dominating hump of Bourlon’s wood-crowned Hill ran across the grain of the country.
On either flank of this area, sometimes at right angles to the curve of our lines, sometimes running parallel to the German lines, ran the Canal du Nord and the Canal de l’Escaut.
The slopes were nowhere very steep, but the levels were everywhere varied by spurs and—so-called—“ravines.” One of these, which lay just within the German lines, and parallel to our front, for some time gave grave concern both to the Tanks and to other arms, who apparently coupled it in their minds with the Grand Cañon of Colorado. Its name sounded so formidable, and it was marked so large on the map! It might well prove a serious obstacle to the progress of Tanks. A series of exhaustive reconnaissances carried out by the Tank Corps, however, dispelled this alarming legend and the “Grand Ravine” stood revealed as being no more than a shallow dry field ditch which could be jumped by any rabbit of reasonable activity.
The German defences, the famous Hindenburg Line, lay wide and strong across the spurs. The main line of resistance had been everywhere well placed on the reverse slopes of the main ridges, and was invisible from our lines. Only from the air and from rare posts of vantage could we see a length of it. There were three lines of trenches, each trench anything up to 15 ft. wide, with an outpost line thrown forward to screen these main defences. In front of the main line lay band upon band and acre upon acre of dense wire; nowhere was it less than 50 yards deep, and here and there it jutted out in great salients flanked by batteries of machine-guns. Never had we before been faced with such a wilderness of wire.
It was calculated that to cut it with artillery would have taken five weeks and cost twenty millions of money.
Not only was the actual “ditch” of the trench believed to be in most places some 12 ft. wide and 18 ft. deep, but at either side, the parados and parapet (each about 2 ft. 6 in. high) were, we had reason to believe, so sloped as to increase the effective width to about 16 to 18 ft.
These were the dimensions of some trenches captured by us at Arras, and for such trenches we had to be prepared.
The space to be cleared was too wide for a Tank. A special means of crossing was, however, devised by the Staff of the Central Workshops at Erin.
This was a special huge fascine made of about seventy-five ordinary bundles of brushwood, strongly compressed and bound by heavy chains.
It was carried on the nose of the machine, and could be released by a touch from inside the Tank by a specially ingenious releasing gear, and dropped neatly into the trench.
The manufacture of the 350 fascines and the fitting of the Tanks with the releasing gear was a piece of work of which the Central Workshops have reason to be proud. They received the order for 350 fascines and 110 Tank sledges on October 24, when they had already for some months been working at high pressure, chiefly upon Tanks salved from the Salient.
To fulfil the new order the shops worked day and night for three weeks.
To make the fascines, 21,000 ordinary stout bundles of brushwood, such as are used for road repairing, were unloaded at the Central Workshops.
Here eighteen Tanks had been specially fitted up, for binding and fastening these into bundles of sixty or seventy.
The Tanks acted in pairs, pulling in opposite directions at steel chains which had been previously wound round and round the bundles.
So great was the pressure thus exerted that, months afterwards, an infantryman in search of firewood, who found one of these fascines and gaily filed through its binding chain, was killed by the sudden springing open of the bundle.
When they were ready, each bundle weighed a ton and a half, and it took twenty of the Chinese coolies employed at the Central Workshops to roll one of them through the mud. On one occasion 144 fascines had to be loaded on to trucks within twenty-four hours. Concurrently with the fascines the Central Workshops achieved the making of the 110 Tank sledges. The whole of the timber needed for this work had to be sawn out of logs. Besides this they repaired and issued 127 Tanks.