effort would have to be made in the East; and as regards Italy,
it was known that her obligation under the Triple Alliance
would become operative only if one of her Allies was defending
itself against attack. On the other hand, the Entente Cordials
between England and France had enabled the latter to concen-
trate her naval effort in the Mediterranean, and the details of
possible cooperation on land, for some years before 1914, had
been studied by the British and French general staffs in concert.
But England reserved to herself complete freedom to decide for
or against intervention if and when the case arose. It was not
till Aug. 2 1914 that Sir Edward Grey engaged that the British
navy would protect the Channel coast of France, and not till
the actual violation of Belgian neutrality by Germany that the
British Government declared war on their own account.
Armies require, for their operations, zones with fronts pro- portionate to their effectives, for it is obvious that they should neither occupy a space so vast as to deprive them of the density necessary for powerful action, nor on the other hand be so over- crowded that their component parts cannot each contribute at the proper time its share in the effort towards a common object. The proper width of these zones depends on the balance of many factors between two reasonable limits; but, above all, it is neces- sary that all the elements that are to be brought into action at the same time should have at their disposal enough routes, more or less parallel, leading to the objective, and that these routes should be approximately at deploying interval apart. Now if Germany attacked France without violating any neutralities, the available width between Switzerland and Luxemburg was practically the same as it had been in 1870. The frontier had changed its position. It is true that Strassburg and Metz were comprised no longer in France but in Germany, and to that extent Germany had gained. But, apart from the fortresses, this frontier was only a conventional line, devoid of strategic interest. The space available for the deployment of the armies, and the distance in a straight line from one neutral frontier to the other, had not altered. Further, not all this space was equally utiliz- able; the Vosges region, for instance, which was very unsuitable for military operations, formed a large part of it. Thus if the available zone of the Franco-German frontier had seemed some- what cramped even in 1870, it was far more so and was be- coming impossibly so for the much larger armies of 1914. If the Germans violated no neutrality, it was out of their power to bring into play the ensemble of their attacking forces, and this fact gave to the French army presumed to be numerically much inferior an immense advantage. With its fortresses of Belfort, Epinal, Toul and Verdun, the French front of contact was very strong, and moreover, organized both to resist any brusque attack of the nature of a " bolt from the blue " and to enable the French army on mobilization to concentrate close up to the frontier without fear of being disturbed. Such, at any rate, was the adopted French view, though the experience of the war, which brought into play destructive engines of a power formerly unimagined, suggests grave doubts as to its accuracy.
In any case, it was clear that, if the Germans wished to obtain in a short time a success decisive enough to put France out of action, or at least to cripple her sufficiently to enable a large part of their forces to be sent against Russia, the violation of one or another national neutrality was a necessity for her that of Switzerland if it was decided to envelop the French right, that of Belgium and of Luxemburg if the French left was to be the object of the -manoeuvre. It was not necessary to violate the neutralities of both flanks, but military opinion was divided as
which would be selected. Each had its partisans in the Ger- nan General Staff, and neither possibility was ignored by the French. At first sight, the passage through Switzerland might eem the more difficult. But, examined more closely, it loses nost of its difficulties. For, in effect, the operation would' con- sist in slicing off such a corner of Switzerland as would give the necessary number of roads, railways and Rhine passages (which ould, of course, be multiplied in the sequel). For this, the Jura gion alone would be enough; and the Swiss forces, massed on flank of the invaders, would be held in check by another
army, presumably Austrian. For it must be borne in mind that the Swiss army could not have been mobilized and concentrated quickly enough to hold the line of the Rhine in sufficient strength to bar access, and that Switzerland possessed not a single fortress to support it. On the other hand, the probability of the Belgian route being the one chosen as it was was indicated by the sys- tematic and prolonged German preparation of rail facilities on that front.
Thus, for many years, it had been regarded as certain that part of the German army of invasion would traverse either Belgium or Switzerland. But it was not possible to foresee the proportioning of forces that would be adopted by the Germans on the thus extended front, for the high development of their railway network, and the consequent flexibility of their concen- tration transports, gave every facility for changes of plan and variants. Further, it was naturally to be presumed that they would make efforts to secure in advance the agreement of the state whose territory they proposed to borrow, and the success or otherwise of these diplomatic moves would necessarily react on the proportioning of forces on the military front. And this was true whether the Germans sought by way of Belgium to reach Paris and deal France a mortal blow by capturing the capital, or by way of Switzerland to cut France in two. In either event, the French armies of the eastern frontier, once turned, would have no alternative but retreat.
The French General Staff naturally foresaw that, since the holding of Russia would devolve upon Austria, the French army would probably have to struggle alone against greatly superior German forces (possibly against a preponderance of almost 7 to 4, as previously stated). The first effort must be directed to- wards establishing a well-prepared and fortified front, propor- tioned to the forces available, and to locate this as near to the Alsace-Lorraine frontier, whence the enemy could launch a direct attack at any moment, as was possible without exposing the army to the risk of a surprise. In the next place, the possi- bilities of attack through both Belgium and Switzerland must be guarded against. To extend the line of battle sufficiently to secure both approaches, or even one of them, in an adequate manner, would involve such a weakening of the whole front as would enable the enemy to attack anywhere with a certainty of : finding only a third to a quarter of the French forces against him. Any such plan was contrary to all the principles of war, and therefore unthinkable. A completely defensive line must extend from Dunkirk to the Vosges, the Donon, and thence, in order to guard the Swiss frontier as far as Bellegarde, to the Rhine; at the rate of one army corps to 7-5 km. of front, this line (750 km.) would require 100 army corps, without reckoning reserves, to secure it or more than four times the whole of the numbers available. If the violation of Belgium could be taken as certain the Swiss frontier need not be considered; the line would then run from Belfort to Dunkirk, a length of 550 km.; but 73 army corps more than the entire French army would even so be required for its defence. However, if the French staff acted on this assumption, the German army would undoubtedly aban- don the Belgian plan and advance through Switzerland; in which case the French army would be turned on the right in such a way that the forces sent to secure the northern frontier could not possibly arrive in time to stop the enemy from crossing the plains of the Sa6ne and coming down into the basin of the Seine. Such a disposition was therefore impossible. The French force must occupy the centre of the line, in Alsace-Lorraine, which was the part most threatened, and be ready to oppose on the north or the south according to the enemy's decision. Accord- ingly, the following dispositions were made. They are the key to the whole of the first period of the war.
The choice of the first line of defence, to be held against direct attack, was determined by the necessity of fixing it at a sufficient distance from the fortress of Metz, the outer defences of which almost touched the frontier, so that the zone of action of the entrenched camp extended into French territory in the Woevre plain, which could not be defended. The most advanced line of battle considered practicable was that of the Meuse slopes,
