352 W A K [STRATEGY. Detention destroy its organic unity, yet a small force may for a time of a large succeec l i n delaying the movements of one very superior to ^ ^ ie ^ l ^ n S po wer of an armv depends upon the number of weapons that it is able to bring to bear upon its enemy. Now, as for rapid movement that does not fatigue the men an army is ordinarily obliged to march along roads, it follows that the number of weapons avail able for fighting in front of the line of march is very small. Hence, though a general may have under his com mand a very large body of troops, representing a very great amount of power when that power is developed, yet as long as he is simply marching forward he cannot imme diately use that power at the point which the head of his column has reached. In order to do so he must bring those men who are far away from the front up to a position in which they can use their arms. Such an operation often takes a very long time. The time becomes much longer if, instead of marching on a road through open country or between hedge-rows, he has great mountain precipices on either side of him, so that he cannot easily get his men out of the path in which they are. Or again, if he finds that it is necessary for him to develop the power of his army in order to force his way across a bridge over a river, it may be necessary for him in the first instance to extend his artillery and infantry along the side of the stream nearest him in order to use his weapons ; and then, when he wants to resume his march, he may have to bring them back again to the bridge. These are instances of the delay which is imposed upon armies which have to force their way through "defiles." Now, if a small force is employed in delaying a larger one, which it does not intend seriously to engage, its object almost always is to induce the larger one thus to " deploy " its force from the march to a position for fighting, purposing itself to escape before the enemy seriously attacks it. It may seem at first that, as the small force has itself necessarily to pass from the march formation to the fighting position and to return again to the march, there is no gain of time. But, in fact, if the successive positions be judiciously chosen for the small force, it is extremely difficult for the general commanding the superior army to know what number of enemies he has before him. If, not wishing to delay the movement of his army, he deploys too small a force, the defender may use his whole power to inflict a crushing defeat upon this before it can be supported. If, on the other hand, he deploys a force sufficient to destroy the body opposed to him, this must involve a long delay, and very probably he will find, when he moves to attack, that the defensive force is already gone, or has left only some light troops to make a show up to the last. By such means again and again in war a small force employed in well-chosen ground has been able to hamper the movements of a superior body and to gain time for other operations. The different applications of this detaining power of small bodies are so numerous that hardly any problems either of strategy or tactics are intelligible unless its nature is understood. The essence of it lies in the smaller body not allowing itself to become so engaged as to have its organic unity destroyed by defeat. Interior The simplest application of this detaining power of small lines. bodies occurs in this way. Suppose, as often happens, that two allied armies, or two parts of the same army, are moving to unite against an enemy. It may happen that by skilful dispositions or the chance of war the general engaged against them is able to interpose between them whilst they are still several marches apart from one another. Suppose now that in a country favourable to such an operation he employs a small portion of his own force to delay the march of one of his opponents, whilst he throws the bulk of his forces against the other. In attempting to defeat this body before it can receive support he holds a position of very great advantage. This is the situation which is commonly described by saying that the general in question is acting on " interior lines " against the two armies opposed to him. But it is vitally important to his success in this matter that he shall succeed in defeating one of his opponents whilst the other is still some marches off, otherwise their union against him on the field of battle may, from the very fact of their striking his position from different directions, prove even more disastrous to him than if he had allowed them to unite before he attacked them. Thus when Napoleon, during the Waterloo campaign, had broken in at Charleroi upon the intended point of concentration of the allied armies, he, with Ney opposing Wellington at Quatre-Bras long before the English army was concentrated, and himself able to act with the bulk of his forces against Bliicher at Ligny before the Prussian army was fully con centrated, was acting in the most perfect way upon interior lines. But, when at Waterloo, whilst he was still engaged with Wellington in his front, Bliicher broke in upon his flank, though the bulk of the French army was still between its opponents, that was a position of disaster. During the 1866 campaign the Prussians crossed the Bohemian mountains in two separate armies, one from Silesia under the crown prince, one from Saxony and Prussia under Prince Frederick Charles. Had the army under the Austrian commander Benedek been concentrated in Bohemia, so that, whilst one part of his forces detained either the crown prince or Prince Frederick Charles, the main body had been thrown against the other, the general would have gained all the advantages of interior lines. But, when on the field of Sadowa, whilst Benedek was still fiercely engaged against the army of Frederick Charles in front, the crown prince broke upon his flank, though the Austrian army was still in one sense between the two Prussian armies, it was so only in a sense disastrous for it. This event, in which an army attempting to take advantage of the separation of two opponents is crushed between them on the field of battle, is described by German soldiers by the phrase that such an army is taken " tactically between them " ("in der taktischen Mitte"). The operation of acting on interior lines was the favourite form of Napoleon s strategy. He would have condemned unhesitatingly the attempt to carry out any plan of campaign which involved such a combination as the Prussians attempted in 1866. But in his day armies were not connected by telegraph. In speaking of the con centration of armies prior to a campaign as necessarily made out of reach of a concentrated enemy there is this reservation to be noted. If two armies acting against a third can so nicely time their union as to strike against the enemy on the field of battle within a few hours of one another, they gain all the advantage of getting their enemy " tactically between them." The difficulties, however, of this nice adjustment of time are so great that no prudent commander would deliberately beforehand arrange his general concentration in this way on the field of battle. Nevertheless, the fact that it is sufficient for the armies to have effected their junction so nearly as to be within reach of mutual support on a field of battle consider ably enlarges the area within which their union can be accomplished. Thus at the beginning of the 1866 campaign the Prussians had fixed the point of junction of their two armies at Gitchin ; but, though it would have been possible for them to have joined their forces on June 30, they did not carry out this actual meeting. They were content with the fact that the two armies were by
June 30 in close supporting distance of one another.