Throughout the war there was an undercurrent of criticism against the dispersion of British forces and dissipation of British energy, and the briefest history of it cannot avoid a certain amount of discursiveness. The reason, if not the justification, is the same in both cases; for happily or unhappily the British Empire is scattered all over the globe, and unless colonies were to be abandoned to enemy attacks and the natural forces of native discontents, they had to be defended in part at least by British troops. Fortunately the task required but a fraction of the military strength which Germany needed to hold Alsace-Lorraine in time of peace, and long before the end Great Britain received from her dominions fourfold the help in Europe that she had to lend them overseas. The rally to the British flag was to us one of the most inspiring, and to the Germans one of the most dispiriting, portents in the war; but it took time to bear its fruits, and meanwhile the cause of civilization had to rely upon the gallantry of French armies and the numerically weak British forces fighting on the Marne and on the Aisne.
The human eye is ever longing to pierce the veil of the future, but it was perhaps as well that men could not foresee, as the Allies drove the Germans across the lower reaches of the Aisne, how long that river would be reddened with the blood of the contending forces. They thought that the tide of invasion would recede as fast as it had advanced, and it was only as the days of German resistance lengthened into weeks, and the weeks into months of the longest battle in history, that staffs and armies and peoples began to grasp the awful potentialities of scientific progress in the art of modern war. The battle without a morrow had long been the ideal consummation for victorious strategy, but no one had yet foreseen the battle without an end and armies without flanks. That sooner or later one or other combatant would be outflanked had been the universal assumption of the strategist; but in the autumn of 1914 the combatant forces gradually extended their fronts in the effort until they rested upon the frontier of Switzerland and the sea, and the deadlock of a deadly embrace began which was not effectively broken until the wrestling of four years wore down the strength of the wrestlers and left the final decision in the hands of new-comers to the European field of battle.
The deadlock was no part of the original German plan, but German forethought during the advance to the Marne had provided entrenchments in the rear for the event of a retreat, and the natural strength of the forest of St. Gobain, the Chemin des Dames, and the Argonne as well as a study of the campaign of 1814 had suggested an obvious line of defence. It was not, however, expected by the Entente higher command which proceeded with its frontal attack on the assumption that the Germans were merely fighting rearguard actions to secure their further retirement; and it was only when the German front refused to budge that pressure spread out to the Allied left wing in an attempt to turn the German right flank, which would have stood more chance of success had it come a fortnight earlier as a first instead of a second thought. An even better alternative might have been to revert to Joffre's original plan, which had failed in August on the Saar, to thrust forward against the Crown Prince and threaten the left of the Germans and the communications of their forces in Belgium and northern France. But it is easier on paper after the event than it was in action at the time to convert an improvised defensive into a considered offensive strategy; and the Germans themselves had occasion during the autumn and the rest of the war to regret that their second thoughts had not come first.
The battle of the Aisne began, like that of the Marne, on Sunday, 13 September. The Germans' retreat had taken them north of the river except at a few bridgeheads, but the river was deep and its crossings were all commanded by fire from German batteries concealed on the slopes rising up from the northern bank. Maunoury's 6th Army attacked on the left from Compigne and the Fort de l'Aigle to Soissons, and several divisions were got across. From Soissons eastward for fifteen miles to Pont-Arcy the line of attack was held by the British Army; the whole of the 4th Division got across near Venizel, and most of the 5th and 3rd Divisions farther east, but the Germans succeeded in holding the bridge at Cond. The 2nd Division was also only partially successful in the region of Chavonne, but the whole of the 1st got across at Pont-Arcy and Bourg. On Monday, Maunoury pressed forward up the heights, capturing Autrches and Nouvron, but, like the British on his right between Vregny and Vailly, he found the German positions impregnable on the plateau. Haig's First Corps was more successful farther east; Vendresse and Troyon were captured and the Chemin des Dames was almost reached. But D'Esperey's 5th French army could make little impression on the Craonne plateau; Foch's 9th was unable to force the Suippe to the east of Reims, and Langle's 4th, while it occupied Souain, was similarly held up in Champagne.
On the 15th the Germans counter-attacked. Maunoury was driven out of Nouvron and Autrches, the British were forced back from Vregny almost to the river, and the Moroccan troops withdrew on Haig's right flank. There was a lull on the 16th, and on the 17th Maunoury recovered the quarries of Autrches; but east of Reims the 9th Army had fallen back from the Suippe, and the Prussian Guard had captured Nogent l'Abbesse and was threatening Foch's connexion with Langle in Champagne. The 18th saw little progress on either side, except along the Oise, where Maunoury had as early as the 15th begun to outflank the German right. This success, coupled with the stalemate along the rest of the front, suggested to Joffre a change of strategy. Numerically the opposing forces were not unequal, but the Germans had all the advantages of position. To attack up carefully protected slopes with a river in the rear and its crossings commanded by the enemy's fire, promised little hope of success, and threatened disaster in case of failure and retreat. Accordingly, Joffre, taking some risks by weakening his centre, began on the 16th to lengthen and strengthen his left by forming two new armies. Castlenau gave up his command of the 2nd to Dubail in Lorraine and took over the new 7th, and a 10th was entrusted to Maud'huy, another of the professors of military history to whom the French and the Russian armies owed so much of their generalship. By the 20th Maunoury had swung his left round until it stretched at a right angle from Compigne north to the west of Lassigny. Castelnau's 7th continued the line north through Roye to the Albert plateau; and on the 30th Maud'huy's 10th took up the tale through Arras to Lens.
But if the impact of equal forces on the Aisne flattened them out towards the west, it had the same effect in the other direction, though here it was the Germans who took the offensive in trying to penetrate Sarrail's flank on the Meuse and thus get behind the whole front of the Allies. Verdun was the nut to be cracked, but Sarrail had been extending its defences so as to put the city beyond the reach of the German howitzers and surrounding it with miles of trenches and wire-entanglements; and the Germans preferred to attempt another method than frontal attack. About the 20th four new corps, chiefly of Wrttemburgers, appeared in Lorraine, bringing their forces up to seven against Sarrail's three; and an attack was made on Fort Troyon on the Meuse which reduced it to a dust-heap but failed to carry the Germans across the river. A more serious onslaught was made on the 23rd against St. Mihiel, which was captured while the neighbouring forts of Paroches and the Camp des Romains were destroyed. But again the Germans were prevented from pushing their advantage, and were left with no more than a wonderful salient which looked on the map like Germany putting out its tongue at France and resisted all efforts to repress this insolence until the closing months of the war.
Having achieved but a sterile success to the south of Verdun, the Crown Prince encountered a greater failure to the west. On 3 October he attacked Sarrail's centre in the forest of the Argonne, seeking to recapture St. Menehould, the headquarters he had abandoned on 14 September. His troops were caught in La Grurie wood and so badly mauled that they temporarily lost Varennes and the main road through the Argonne to Verdun. Foiled in both these directions, the Germans revenged themselves by bombarding Reims in the centre and ruining its cathedral; "the commonest, ugliest stone," wrote a German general, "placed to mark the burial-place of a German grenadier is a more glorious and perfect monument than all the cathedrals in Europe put together." The bombardment did not help them much; Neuvillette, which they had seized two miles north of Reims, was lost again on 28 September, and the French also recovered Prunay, the German occupation of which had driven a wedge between Foch's and Langle's armies. On the other hand, Berry-au-Bac, where the great road crossed the Aisne and the French often reported progress, remained in German hands for four years longer. Both sides were now firmly entrenched, and their armies were learning that new art of trench warfare which was to tax their ingenuity, test their endurance, and drain their strength, until years later this war of positions once more gave place to a war of movement. The lines had become stabilized, and between Reims and the Alps they did not alter by half a dozen miles at any point from September 1914 until September 1918. The question of October was whether and where they would be fixed between the Aisne and the sea.
Joffre's outflanking move was promptly countered, if not indeed anticipated, by the German higher command, and in the first days of October there was a general drift of German forces towards their right and the Channel ports. Most and the best of the new levies were sent into Belgium, and the stoutest troops in the fighting line were shifted from East to West. Alsace was almost denuded; the Bavarians were moved from Lorraine towards Lille and Arras, and the Duke of Wrttemberg into Belgian Flanders. Von Bulow was sent to face Castelnau and Maud'huy between the Oise and the Somme, and only Von Kluck and the Crown Prince with a new general, Von Heeringen, from Alsace were left to hold the line of the Aisne. Von Moltke was superseded by Falkenhayn, and a new phase came over German strategy. The knock-out blow against France had failed, and the little British Army threatened to grow. France had been the only foe the Germans had counted in the West, but a new enemy was developing strength, and the German front was turned to meet the novel danger.
The British Army made a movement which was sympathetic with this change and symptomatic of the future course of the war. It was clearly out of place along the Aisne in trenches which could be held by French territorials and where its long communications crossed those of three French armies. It was needed in Flanders close to its bases and to the Channel ports which the Germans had now resolved to seize in the hope of cutting or straining the Anglo-French liaison and furthering their new campaign on land and sea against their gathering British foes. The idea had occurred to Sir John French before the end of September, and on the 29th he propounded it to Joffre; Joffre concurred, called up an 8th Army under D'Urbal to support and prolong the extension of the line into Flanders, and placed Foch in general charge of the operations north of Noyon. The transport began on 3 October and was admirably carried out, though some of the ultra-patriotic English newspapers did their best to help the enemy by their enterprise in evading the Censor and giving news of the movement to the public; for if business was business to the profiteer, news was news to its vendors.