The main offensive by the III. and V. Armies terminated on
the i4th; the artillery support was becoming inadequate, and
the troops in front line required relief. A remarkable success
had been gained; the British front line had been moved forward
some 4m., and some 13,000 prisoners and 200 guns had been
captured. It was not possible, however, to break off the battle,
seeing that the French offensive was on the point of being
launched, and it was important that the full pressure of the
British operations should be maintained in order to assist jt.
Much had already been accomplished; the enemy had been
compelled to pour men and guns into the breach, and a large
hostile concentration in the battlefield was in process of being
effected.
The only offensive action taken by the Germans during this period in this area occurred on April 15, when they attacked the British position from Hermies to Noreuil with 16 battalions. An initial success, in which some of the British battery positions were overrun, was at once neutralized by a counterstroke which restored the line.
On April 16 the French launched their main offensive on the Aisne. The decisive results which had been looked for were not achieved; there was no rapid break through or exploitation by a reserve army of manoeuvre. On the contrary, ragged fighting took place which continued until May 5, and the French armies, worn out by more than two years of heavy fighting, were in no condition to sustain an exhausting offensive. The unified command was in the hands of a French general who had planned and conducted operations which proved to be unsuccessful. From April 15 to May 5 the British continued their operations on the Arras- Vimy front at the request of the French and in order to carry out the r&le of absorbing the enemy's reserves. During this period attacks were executed by the British on April 23 and 28 and on May 3 and 5, with the result that the line was pushed forward to include Qucmappe-Gavrelle and Arleux, and some 6,000 additional prisoners and 50 guns were taken. On May 5 the great offensive operations on the Aisne and Scarpe were brought to a close, and on May 15 Gen. Nivelle was relieved of his command. This brought to naught the effort to obtain unity of command, and the operations provided a warning as to the dangers involved where armies of different nationalities are concerned.
Such was the story of a great and successful British effort under conditions of abnormal difficulty. The Russian Revolution had declared itself, the French armies had broken down, the enemy was recovering his reserve power, and the period of the year was getting late for the transference of operations elsewhere. The British field-marshal commander-in-chief then decided immediately that it was necessary to continue on the offensive and to transfer the theatre of operations to the north.
(H) The Relief Offensive in Front of Lens.—The great British offensive in Flanders was launched on July 31 1917 and continued to be pressed throughout the autumn. Towards the middle of Aug. a slight improvement took place in the weather, and advantage was taken of this to deliver the second attack E. of Ypres. As it was desirable to prevent the enemy from weakening the remainder of the front so as to effect a greater concentration in Flanders, it was desirable and even necessary to threaten and undertake operations of a minor character at various points to pin the enemy's reserves. A highly successful operation was carried out in the neighbourhood of Lens, and the threat to this town undoubtedly had the effect of preventing the enemy from concentrating the whole of his attention and resources on the main battle-front.
At 4:25 A.M. on Aug. 15 the ist and 2nd Canadian Divs. attacked on a front of 4,000 yd. S.E. and E. of Loos. The objectives consisted of the strongly fortified Hill 70, which had been reached, but not held, in the battle of Loos in Sept. 1915, and the mining suburbs of Cite Ste. Elisabeth, Cite St. Emile, and Cite St. Laurent together with Bois Rase and half Bois Hugo. The observation from Hill 70 had been very useful to the enemy, and in the possession of the British, would materially increase their command over the defences of Lens. Practically the whole of these objectives were gained rapidly at light cost, and in exact accordance with plan. Only at the farthest limit of the advance a short length of German trench W. of Cite St. Auguste resisted the first assault. This position was again attacked on the afternoon of the following day and captured after a fierce struggle lasting far into the night. A number of local counter-attacks on the morning of Aug. 15 were repulsed, and in the evening a powerful attack delivered across the open by a German reserve division was broken up with heavy loss. In addition to the enemy's other casualties, 1,120 from three German divisions were captured by the British. Thus not only was the British position improved but three German divisions, which might have been used in roulement on the Flanders front, were severely handled, and the enemy received a lesson which would prevent him from unduly weakening the defensive fronts.
(I) The Battle of Cambrai (Nov.-Dec., 1917).—The repeated attacks delivered by the British in Flanders over a period of more than three months had brought about a large concentration of the enemy's forces in that area, with a con- sequent reduction of his strength and garrisons in other sectors of his front. The British object in the operations at Cambrai, which took place on Nov. 20 1917, was to gain a local success by a surprise attack at a point where the enemy did not expect it, and on a front which had already been weakened, and thus disarrange the enemy's plans of withdrawing troops from France to operate in Italy. The sector opposite Cambrai had been carefully selected as the most suitable. The ground there was, on the whole, favourable for the employment of tanks which were to play an important part in the enterprise. If, after breaking through the German defence systems on this front, the high ground at Bourlon could be secured and a defensive flank established facing E., and opportunity should be created of exploiting the situation towards the N.W., the capture of Cambrai itself was subsidiary.
As a result of the pressure in Flanders and the Russian Revolution, large German forces had already been brought from the Russian front, partly in exchange for exhausted divisions and partly as additional reinforcements. Moreover, it was certain that heavy German reinforcements would continue to be railed to the western front during the winter. These troops would be largely utilized to strengthen the weakened sector, and if the opportunity, which existed, to deliver a surprise attack at an early date under favourable conditions were not taken advantage of, it would certainly lapse. Against this argument in favour of immediate action must be weighed the fact that the conditions of the Flanders struggle had severely taxed the strength of the British forces, and that the losses, which had not yet been made good, had been heavy.
On the other hand the resources required for the operation were not great, seeing that the force to be employed must be small, for, owing to the requirements of surprise and secrecy, any considerable concentration of troops would be impossible to maintain. The success of the enemy's operations in Italy, too, added force to the arguments in favour of undertaking the operation; although the means available had been reduced by the despatch of troops to the Italian front, the situation on that front was critical, the Italians having been driven back between Oct. 24 and Nov. 10 from the Isonzo to the Piave.
After consideration of these factors, it was decided, by the British command, to undertake the operation, and the execution was entrusted to the III. Army. The general plan of attack was to dispense with previous artillery preparation, and to depend on tanks, of which there would be nearly 500 available, to break down the enemy's wire and cover the infantry advance. No previous abnormal artillery fire was to take place and no registration of guns or any action which might indicate to the enemy that an attack was impending. The infantry was specially trained to work in combination with tanks, and the whole operation depended for success on secrecy and on bold, determined and rapid action.
The German defences on the selected front between Vendhuille on the Scheldt canal and the river Sensée comprised the three
