On War

by Carl von Clausewitz

We have now to consider the difference which takes place in respect to the question of subsistence in war, according as the action is offensive or defensive.

The defensive is in a position to make uninterrupted use of the subsistence which he has been able to lay in beforehand, as long as his defensive act continues. The defensive side therefore can hardly be in want of the necessaries of life, particularly if he is in his own country; but even in the enemy’s this holds good. The offensive on the other hand is moving away from his resources, and as long as he is advancing, and even during the first weeks after he stops, must procure from day to day what he requires, and this can very rarely be done without want and inconvenience being felt.

This difficulty is felt in its fullest force at two particular periods, first in the advance, before the decision takes place; then the supplies of the defensive side are all at hand, whilst the assailant has been obliged to leave his behind; he is obliged to keep his masses concentrated, and therefore cannot spread his army over any considerable space; even his transport cannot keep close to him when he commences his movements preliminary to a battle. If his preparations have not been very well made, it may easily happen at this moment that his army may be in want of supplies for several days before the decisive battle, which certainly is not a means of bringing them into the fight in the highest state of efficiency.

The second time a state of want arises is at the end of a victorious career, if the lines of communication begin to be too long, especially if the war is carried on in a poor, sparsely-populated country, and perhaps also in the midst of a people whose feelings are hostile. What an enormous difference between a line of communication from Wilna to Moscow, on which every carriage must be forcibly seized, and a line from Cologne by Liége, Louvain, Brussels, Mons, and Valenciennes to Paris, where a mercantile contract or a bill of exchange would suffice to procure millions of rations.

Frequently has the difficulty we are now speaking of resulted in obscuring the splendour of the most brilliant victories, reduced the powers of the victorious army, rendered retreat necessary, and then by degrees ended in producing all the symptoms of a real defeat.

Forage, of which, as we have before said, there is usually at first the least deficiency, will run short soonest if a country begins to become exhausted, for it is the most difficult supply to procure from a distance, on account of its bulk, and the horse feels the effect of low feeding much sooner than the man. For this reason, an over-numerous cavalry and artillery may become a real burden, and an element of weakness to an army.

CHAPTER XV.
Base of Operations

If an army sets out on any expedition, whether it be to attack the enemy and his theatre of war, or to take post on its own frontier, it continues in a state of necessary dependence on the sources from which it draws its subsistence and reinforcements, and must maintain its communication with them, as they are the conditions of its existence and preservation. This dependence increases in intensity and extent in proportion to the size of the army. But now it is neither always possible nor requisite that the army should continue in direct communication with the whole of its own country; it is sufficient if it does so with that portion immediately in its rear, and which is consequently covered by its position. In this portion of the country then, as far as necessary, special depôts of provisions are formed, and arrangements are made for regularly forwarding reinforcements and supplies. This strip of territory is therefore the foundation of the army and of all its undertakings, and the two must be regarded as forming in connection only one whole. If the supplies for their greater security are lodged in fortified places, the idea of a base becomes more distinct; but the idea does not originate in any arrangement of that kind, and in a number of cases no such arrangement is made.

But a portion of the enemy’s territory may also become a base for our army, or, at least, form part of it; for when an army penetrates into an enemy’s land, a number of its wants are supplied from that part of the country which is taken possession of; but it is then a necessary condition that we are completely masters of this portion of territory, that is, certain of our orders being obeyed within its limits. This certainty, however, seldom extends beyond the reach of our ability to keep the inhabitants in awe by small garrisons, and detachments moving about from place to place, and that is not very far in general. The consequence is, that in the enemy’s country, the part of territory from which we can draw supplies is seldom of sufficient extent to furnish all the supplies we require, and we must therefore still depend on our own land for much, and this brings us back again to the importance of that part of our territory immediately in rear of our army as an indispensable portion of our base.

The wants of an army may be divided into two classes, first those which every cultivated country can furnish; and next those which can only be obtained from those localities where they are produced. The first are chiefly provisions, the second the means of keeping an army complete in every way. The first can therefore be obtained in the enemy’s country; the second, as a rule, can only be furnished by our own country, for example men, arms, and almost all munitions of war. Although there are exceptions to this classification in certain cases, still they are few and trifling, and the distinction we have drawn is of standing importance, and proves again that the communication with our own country is indispensable.