It is probably not realised that this was strategically the most important offensive movement the Germans had made in the western theatre of war since their advance upon Paris. Yet that undoubtedly was the fact. Had the movement succeeded it must not only have given them control of the north-east coast of France as far probably as Havre, but it must have rolled up the Allied line as far as Noyon. The whole original scheme of turning the Allies' left flank would have been within realisation. The movement did not succeed. It was met by a counter-move probably as unexpected by the Germans as it was bold. The counter-move was the transfer of the British army from the Aisne. Recognising the decisive character of these operations, General Joffre had entrusted the control of affairs on this part of the front to General Foch, not only one of the ablest among the able soldiers whom this war has shown the French Army to possess, but one of the most brilliant authorities on the science of modern military tactics. As he had met the situation magnificently at Sezanne, so now he met it with equal resource under circumstances hardly less critical. There were now three French armies on the German flank, and they fought as they were led with a skill equal to their valour. Yet the necessity remained for a great counter-stroke. In view of that necessity the idea occurred to Sir John French to transfer the British army, a proposal to which General Joffre at once agreed. It is beyond the scope of this volume to enter into details of the new great battle which, beginning with the arrival of the British troops, culminated in the heroic defence of Ypres. Justice could not be done to that great and memorable feat of arms in a brief summary. Suffice it to say that here, on the great coalfield of northern France, in a labyrinth of railway sidings and canals, villages and lanes, pit heaps, and factories, the British troops, helped by the French cavalry, after furious fighting, drove back the Germans from the Aa and the Lys and took up a line continuing the outflanking positions from La Bassée to Ypres in Belgium. A third effort of the Germans to outflank the outflanking line was directed across the Yser. This was the last attempt of the kind that could be made. Its success was consequently vital, and its failure equally disastrous. Again it illustrates the fact that the Germans sacrifice neither money nor lives without good cause. The fighting on the Yser was as deadly for the enemy as the fighting round Rheims. Coincidently, however, with these movements were others of a different kind. The official _communiqués_, covering the two kinds of movements as the evidences of them appeared day by day, have naturally led to a certain amount of mystification--not intentional, but inevitable from the brevity and caution of these statements and the fact that they cover separately only the operations of a few hours.