THE attack and defence of a convoy form a subject of tactics: we should, therefore, have nothing to say upon the subject here if it was not necessary, first, to demonstrate generally, to a certain extent, the possibility of the thing, which can only be done from strategic motives and relations. We should have had to speak of it in this respect before when treating of the defence, had it not been that the little which can be said about it can easily be framed to suit for both attack and defence, while at the same time the first plays the higher part in connection with it.
A moderate convoy of three or four hundred wagons, let the load be what it may, takes up half a mile, a large convoy is several miles in length. Now, how is it possible to expect that the few troops usually allotted to a convoy will suffice for its defence? If to this difficulty we add the unwieldy nature of this mass, which can only advance at the slowest pace, and which, besides, is always liable to be thrown into disorder, and lastly, that every part of a convoy must be equally protected, because the moment that one part is attacked by the enemy, the whole is brought to a stop, and thrown into a state of confusion, we may well ask,—how can the covering and defence of such a train be possible at all? Or, in other words, why are not all convoys taken when they are attacked, and why are not all attacked which require an escort, or, which is the same thing, all that come within reach of the enemy? It is plain that all tactical expedients, such as Templehof's most impracticable scheme of constantly halting and assembling the convoy at short distances, and then moving off afresh: and the much better plan of Scharnhorst, of breaking up the convoy into several columns, are only slight correctives of a radical evil.
The explanation consists in this, that by far the greater number of convoys derive more security from the strategic situation in general, than any other parts exposed to the attacks of the enemy, which bestows on their limited means of defence a very much increased efficacy. Convoys generally move more or less in rear of their own army, or, at least, at a great distance from that of the enemy. The consequence is, that only weak detachments can be sent to attack them, and these are obliged to cover themselves by strong reserves. Added to this the unwieldiness itself of the carriages used, makes it very difficult to carry them off; the assailant must therefore, in general, content himself with cutting the traces, taking away the horses, and blowing up powder-wagons, by which the whole is certainly detained and thrown into disorder, but not completely lost; by all this we may perceive, that the security of such trains lies more in these general relations than in the defensive power of its escort. If now to all this we add the defence of the escort, which, although it cannot by marching resolutely against the enemy directly cover the convoy, is still able to derange the plan of the enemy's attack; then, at last, the attack of a convoy, instead of appearing easy and sure of success, will appear rather difficult, and very uncertain in its result.
But there remains still a chief point, which is the danger of the enemy's army, or one of its corps, retaliating on the assailants of its convoy, and punishing it ultimately for the undertaking by defeating it. The apprehension of this, puts a stop to many undertakings, without the real cause ever appearing; so that the safety of the convoy is attributed to the escort, and people wonder how a miserable arrangement, such as an escort, should meet with such respect. In order to feel the truth of this observation, we have only to think of the famous retreat which Frederick the Great made through Bohemia after the siege of Olmutz, 1758, when the half of his army was broken into a column of companies to cover a convoy of 4,000 carriages. What prevented Daun from falling on this monstrosity? The fear that Frederick would throw himself upon him with the other half of his army, and entangle him in a battle which Daun did not desire; what prevented Laudon, who was constantly at the side of that convoy, from falling upon it at Zischbowitz sooner and more boldly than he did? The fear that he would get a rap over the knuckles. Ten miles from his main army, and completely separated from it by the Prussian army, he thought himself in danger of a serious defeat if the king, who had no reason at that time to be concerned about Daun, should fall upon him with the bulk of his forces.
It is only if the strategic situation of an army involves it in the unnatural necessity of connecting itself with its convoys by the flank or by its front that then these convoys are really in great danger, and become an advantageous object of attack for the enemy, if his position allows him to detach troops for that purpose. The same campaign of 1758 affords an instance of the most complete success of an undertaking of this description, in the capture of the convoy at Domstadtel. The road to Neiss lay on the left flank of the Prussian position, and the king's forces were so neutralised by the siege and by the corps watching Daun, that the partizans had no reason to be uneasy about themselves, and were able to make their attack completely at their ease.
When Eugene besieged Landrecy in 1712, he drew his supplies for the siege from Bouchain by Denain; therefore, in reality, from the front of the strategic position. It is well known what means he was obliged to use to overcome the difficulty of protecting his convoys on that occasion, and in what embarrassments he involved himself, ending in a complete change of circumstances.
The conclusion we draw, therefore, is that however easy an attack on a convoy may appear in its tactical aspect, still it has not much in its favour on strategic grounds, and only promises important results in the exceptional instances of lines of communication very much exposed.