From the strategy on the German side let us now turn to that on the side of the French. Between them a fundamental distinction at once appears.

Of both the aim was similar—to compel the other side to fight under a disadvantage. In that way strategy helps to ensure victory, or to lessen the consequences of defeat.

The strategy of the German General Staff, however, was from the outset obvious. The strategy of General Joffre was at the outset a mystery. Only as the campaign went on did the French scheme of operations become apparent. Even then the part of the scheme still to come remained unfathomable.

It has been assumed that with the employment of armies formed of millions of men the element of surprise must be banished. That was a German theory. The theory is unsound. Now, as ever, intellect is the ultimate commanding quality in war.

In truth, the factor of intellect was never more commanding than under conditions of war carried on with mass armies.

Reflect upon the difference between an opponent who, under such conditions, is able to fathom and to provide against hostile moves, and the opponent who has to take his measures in the dark as to hostile intentions.

The former can issue his orders with the reasonable certainty that they are what the situation will call for. Never were orders and instructions more complex than with modern armies numbering millions; never were there more contingencies to provide against and to foresee. To move and to manipulate these vast masses with effect, accurate anticipation is essential. Such complicated machines cannot be pushed about on the spur of the moment when a general suddenly wakes up to a discovery.

It follows that to conduct a campaign with mass armies there must either be a plan which you judge yourself strong enough in any event to realise or a plan which, because your opponent cannot fathom it, must throw him into complete confusion. The former was the German way; the latter the French.

That General Joffre would try in the first place to defeat the German armies in detail was not, of course, one of the surprises, because it is elementary, but that he should have so largely succeeded in defeating them was a surprise.

In these encounters, as during later battles of the campaign, the French troops discovered a cohesion and steadiness and a military habit of discipline assumed to be foreign to their temperament. But their units had been trained to act together in masses on practical lines. Of the value of that training General Joffre was well aware.

He knew also that success in the earlier encounters, which that training would go far to ensure, must give his troops an invaluable confidence in their own quality.

There were, however, two surprises even more marked. One of these was the quite unexpected use made of the fortified frontier; the other, associated with it, was that of allowing the Germans to advance upon Paris with an insufficient force, in the belief that French movements were being conformed to their own.

Undoubtedly as regards the fortified frontier the belief prevailed that the chief difficulty would be that of destroying its works with heavy guns. It had never been anticipated that the Germans might be prevented from getting near enough for the purpose. But in the French strategy Verdun, Toul, and Belfort were not employed as obstacles. They were employed as the fortified bases of armies. Being fortified, these bases were safe even if close to the scene of operations. Consequently the lines of communication could be correspondingly shortened, and the power and activity of the armies dependent on them correspondingly increased. So long as these armies remained afoot, the fortresses were unattackable. Used in that way, a fortress reaches its highest military value.

The strategy adopted by General Joffre in association with the German advance upon Paris is one of the most interesting phases of the war. His tactics were to delay and weaken the first and driving formation of the German chain of armies; his strategy was, while holding the tail of that chain of armies fast upon the fortified frontier, to attract the head of it south-west. In that way he at once weakened the chain and lengthened out the German communications. Not merely was the position of the first German army the worse, and its effective strength the less, the further it advanced, thus ensuring its eventual defeat, but in the event of defeat retirement became proportionally more difficult. The means employed were the illusion that this army was driving before it, not a wing of the Allied forces engaged merely in operations of delay, but forces which, through defeat, were unable to withstand its march onward.

It cannot now be doubted that the Germans had believed themselves strong enough to undertake the investment of Paris concurrently with successful hostilities against the French forces in the field. But by the time General von Kluck's army arrived at Creil, the fact had become manifest that those two objectives could not be attempted concurrently. The necessity had therefore arisen of attempting them successively.

In face of that necessity the choice as to which of the two should be attempted first was not a choice which admitted of debate. Defeat of the French forces in the field must be first. Without it, the investment of Paris had clearly become an impossibility. How far it had become an impossibility will be realised by looking at the position of the German armies.

Five of them were echeloned across France from Creil, north-east of Paris, to near the southern point of the Argonne.

The army of von Kluck was between Creil and Soissons, with advanced posts extended to Meaux on the Marne.

The army of von BÜlow was between Soissons and Rheims, with advanced posts pushed to ChÂteau-Thierry, also on the Marne.

The army of von Hausen held Rheims and the country between Rheims and Chalons, with advanced posts at Epernay.

The army of Duke Albert, with headquarters at Chalons, occupied the valley of the Marne as far as the Argonne.

The army of the Crown Prince of Prussia, with headquarters at St. Menehould, held the Argonne north of that place, with communications passing round Verdun to Metz.

If the line formed by these armies be traced on the map, it will be found to present from Creil to the southern part of the Argonne a great but somewhat flattened arc, its curvature northwards. Then from the southern part of the Argonne the line will present a sharp bend to the north-east.

Now these five armies, refortified by reserves, comprised nineteen army corps, plus divisions of cavalry—a vast force aggregating well over one million men, with more than 3,000 guns. Powerful as it appeared, however, this chain of armies was hampered by that capital disadvantage of being held fast by the tail. Held as it was, the chain could not be stretched to attempt an investment of Paris without peril of being broken, and the great project of defeating and enveloping the Allied forces was impossible.

No question was during the first weeks of the war more repeatedly asked than why, instead of drafting larger forces to the frontier of Belgium, General Joffre should have made what seemed to be a purposeless diversion into Upper Alsace, the Vosges, and Lorraine.

The operations of the French in those parts of the theatre of war were neither purposeless nor a diversion.

On the contrary, those operations formed the crux of the French General's counter-scheme.

Their object was, as shown, to prevent the Germans from making an effective attack on the fortified frontier. General Joffre well knew that in the absence of that effective attack, and so long as the German echelon of armies was pinned upon the frontier, Paris could not be invested. In short, the effect of General Joffre's strategy was to rob the Germans of the advantages arising from their main body having taken the Belgian route.

On September 3, then, the scale of advantage had begun to dip on the side of the defence. It remained to make that advantage decisive. The opportunity speedily offered. Since the opportunity had been looked for, General Joffre had made his dispositions accordingly, and was ready to seize it.

Let it be recalled that the most vulnerable and at the same time the most vital point of the German echelon was the outside or right flank of the leading formation, the force led by General von Kluck. Obviously that was the point against which the weight of the French and British attack was primarily directed.

To grasp clearly the operations which followed, it is necessary here to outline the natural features of the terrain and its roads and railways. For that purpose it will probably be best to start from the Vosges and take the country westward as far as Paris.

On their western side the Vosges are buttressed by a succession of wooded spurs divided by upland valleys, often narrowing into mere clefts called "rupts." These valleys, as we move away from the Vosges, widen out and fall in level until they merge with the upper valley of the Moselle. If we think of this part of the valley of the Moselle as a main street, and these side valleys and "rupts" as culs-de-sac opening off it, we form a fairly accurate notion of the region.

From the valley of the upper Moselle the valley of the upper Meuse, roughly parallel to it farther west, is divided by a ridge of wooded country. Though not high, this ridge is continuous.

On the points of greatest natural strength commanding the roads and railways running across the ridge, and mostly on the east side of the valley of the Meuse, had been built the defence works of the fortified frontier.

Crossing the valley of the Meuse we come into a similar region of hills and woods, but this region is, on the whole, much wilder, the hills higher, and the forests more extensive and dense. The hills here, too, form a nearly continuous ridge, running north-north-west. The highlands east of the Meuse sink, as we go north, into the undulating country of Lorraine, but the ridge on the west side of the Meuse extends a good many miles farther. This ridge, with the Meuse flowing along the east side of it and the river Aire flowing along its west side, is the Argonne. It is divided by two main clefts. Through the more northerly runs the main road from Verdun to Chalons; through the more southerly the main road from St. Mihiel on the Meuse to Bar-le-Duc, on the Marne.

Thus from the Vosges to the Aire we have three nearly parallel rivers divided by two hilly ridges.

North of Verdun the undulating Lorraine country east of the Meuse again rises into a stretch of upland forest. This is the Woevre.

Now, westward of the Argonne and across the Aire there is a region in character very like the South Downs in England. It extends all the way from the upper reaches of the Marne north-west beyond the Aisne and the Oise to St. Quentin. In this open country, where the principal occupation is sheep grazing, the lonely main roads run across the downs for mile after mile straight as an arrow. Villages are far between. The few towns lie along the intersecting valleys.

But descending from the downs into the wide valley of the Marne we come into the region which has been not unaptly called the orchard of France, the land of vineyards and plantations, and flourishing, picturesque towns; in short, one of the most beautiful spots in Europe. The change from the wide horizons of the solitary downs to the populous and highly-cultivated lowlands is like coming into another world.

From the military point of view, however, the important features of all this part of France are its roads and rivers, and most of all its rivers.

The three main waterways, the Oise, the Marne, and the Seine, converge as they approach Paris. Between the Oise and the Marne flows the main tributary of the Oise, the Aisne. Also north of the Marne is its tributary, the Ourcq; south of the Marne flows its tributaries, the Petit Morin and the Grand Morin. All join the Marne in the lower part of the valley not far from Paris. Between the Marne and the Seine flows the Aube, a tributary of the Seine. The country between the Marne and the Seine forms a wide swell of land. It was along the plateaux forming the backbone of this broad ridge that the Battle of the Marne was, for the most part, fought.

That brings us to the question of the roads.

Eastward from Paris, along the valley of the Marne, run three great highways. The most northerly, passing through Meaux, La FertÉ-sous-Jouarre, ChÂteau Thierry, and Epernay to Chalons, follows nearly the same course as the river, crossing it at several points to avoid bends. The next branches off at La FertÉ-sous-Jouarre, and also runs to Chalons by way of Montmirail. The third, passing through La FertÉ-Gaucher, Sezanne, FÈre Champenoise, and Sommesons to Vitry-le-FranÇois, follows the backbone of country already alluded to. All these great roads lead farther east into Germany, the northerly and the middle roads to Metz and the valley of the Moselle, the third road to Nancy and Strasburg.

Now, it must be manifest to anybody that command of these routes, with command of the railways corresponding with them, meant mastery of the communications between Paris and the French forces holding the fortified frontier all the way from Toul to Verdun.

If, consequently, the invading forces could seize and hold these routes and railways, and, as a result, which would to all intents follow, could seize and hold the great main routes and the railways running eastward through the valley of the Seine from Paris to Belfort, the fortified frontier—the key to the whole situation—would in military phrase, be completely "turned." Its defence consequently would have to be abandoned.

Not only must its defence have been abandoned, with the effect of giving freedom of movement to the German echelon, but, that barrier removed, the German armies would no longer be dependent for munitions and supplies on the route through Belgium. They could receive them just as conveniently by the route through Metz. Their facilities of supply would be doubled.

It will be seen, therefore, to what an extent the whole course of the war hung upon this great clash of arms on the Marne. German success must have affected the future of operations alike in the western theatre and in the eastern.

But there is another feature of the roads in the valley of the Marne which is of consequence. Great roads converge into it from the north. Sezanne has already been mentioned. It is half-way along the broad backbone dividing the valley of the Marne from the valley of the Seine. Five great roads meet there from La FertÉ-sous-Jouarre, Soissons, Rheims, Chalons, Verdun, and Nancy. Hence the facility for massing at that place a huge body of troops.

It will be seen, therefore, that in making Sezanne the point at which they aimed their main blow at the whole French scheme of defence, the Germans had selected the spot where the blow would, in all probability, be at once decisive and possibly fatal. Clearly they had now grasped, at all events in its main intention, the strategy of the French general. They saw that he was using the fortified frontier to checkmate their Belgian plan.

Summing up the consequences, had success attended the stroke we find that it would have:

Opened to the invaders the valley of the Seine.

Turned the defence of the fortified frontier.

Released the whole of the German armies.

Given them additional, as well as safer, lines of supply from Germany.

Enabled the German armies to sweep westward along the valley of the Seine, enveloping or threatening to envelop the greater part of the French forces in the field.