I hold, therefore, that such circumstances render a disturbance of the rear communications of an army an important matter. It will often do the opponent more damage, and contribute more to a favourable decision of arms than the intervention of a few cavalry divisions in the decisive battle itself.
The one does not, of course, exclude the possibility of the other. General Stuart, in the campaign of Gettysburg, rode all round the hostile army, broke up its communications, drew hostile troops away from the decisive point, and was yet in his place on the wing of the army on the day of battle. What this man performed with cavalry and the inestimable damage he inflicted on his opponent are worth studying. The fortune of war, which lay in might and in the nature of things, he could not turn. Nor could he bring the advance of an army to a standstill, because at that period and under those circumstances it was possible for the army of the North to live, at least for a time, upon the country. If we regard his achievement by the light of modern conditions, we shall certainly not fall into the error of underestimating the value of such enterprises. If we compare it with the performances of cavalry upon the battlefield in the latest war, we will be able to obtain a true impression of the degree of importance of modern cavalry action.
I am inclined to think that such enterprises will be of altogether extraordinary significance in a future war; least so, perhaps, during the earlier battles resulting from the concentration, when it will be difficult to get round the flanks of the enemy, but more so during the subsequent course of operations. We have only to imagine what the decisive consequences must have been if General von Werder, and, later, General von Manteuffel, had been in a position to continually interrupt the rear communications of the army of Bourbaki. In all probability the latter must have capitulated long before it reached the Swiss frontier, always granting that it was successful in getting so far as the battlefield of the Lisaine. The whole crisis of this campaign, which was very nearly ending in the defeat of the Germans, would thus possibly have been avoided.
There are plenty of examples of this. To indicate only one from the history of the latest war, I would call to mind the undertaking of the Russians against the rear communications of the Japanese army.
If this undertaking had been actually directed against the only railway at the disposal of the Japanese army, if it had been carried through by throwing into the scale the whole fighting strength of a really mobile and efficient cavalry, and if it had thereby succeeded in interrupting the supplies of the Japanese army for a period, the whole course of the campaign might have been changed. Victory in this tremendous conflict hung continually in the balance, and it needed but little more weight on either side to turn the scale of the fortunes of war.
The importance of such raids in modern war should not therefore, in my opinion, be underestimated. They are capable rather of exercising enormous influence on the course of events.
Rules, however, cannot be laid down for their conduct. The Regulations indicate, shortly, that attention must be paid to the transport of sufficient ammunition and supplies, and here, indeed, move in the right direction. It is absolutely indispensable that a cavalry mass destined to carry out such an enterprise should be independent of what it may find in the country and be perfectly free of movement.
The supply and ammunition columns, however, which accompany it, must also be so mobile that they are able to follow the troops closely, even at a rapid pace, as otherwise they will run the danger of falling into the hands of the enemy. The whole force designed for the enterprise must be able to advance rapidly as a concrete whole, and should not be allowed to take up too much room. Resources found upon the enemy's lines of communication and magazines captured must be used for the sustenance of the troops as far as possible. It will then be able to reserve the supplies carried for critical times or for a further turning movement. Any of the enemy's supplies which are not used must be ruthlessly laid waste. His railways and magazines, particularly any important engineering structures, must be thoroughly destroyed, the necessary explosives being carried in sufficient quantities.
In contrast to Stuart's raids, however, one must count on meeting not inconsiderable bodies of the enemy's communication troops, which will probably be capable of rapid reinforcement. This entails corresponding preventive measures.