On War

by Carl von Clausewitz

3rd. In strategy, on account of the extent of space embraced, the efficacy of interior, that is of shorter lines, is much greater, and this forms a great safeguard against attacks from several directions.

4th. A new principle makes its appearance in the sensibility, which is felt as to lines of communication, that is in the effect which is produced by merely interrupting them.

Now it confessedly lies in the nature of things, that on account of the greater spaces in strategy, the enveloping attack, or the attack from several sides, as a rule is only possible for the side which has the initiative, that is the offensive, and that the defensive is not in a condition, as he is in tactics, in the course of the action, to turn the tables on the enemy by surrounding him, because he has it not in his power either to draw up his forces with the necessary depth relatively, or to conceal them sufficiently: but then, of what use is the facility of enveloping to the offensive, if its advantages are not forthcoming? We could not therefore bring forward the enveloping attack in strategy as a principle of victory in general, if its influence on the lines of communication did not come into consideration. But this factor is seldom great at the first moment, when attack and defence first meet, and while they are still opposed to each other in their original position; it only becomes great as a campaign advances, when the offensive in the enemy’s country is by degrees brought into the condition of defensive; then the lines of communication of this new party acting on the defensive, become weak, and the party originally on the defensive, in assuming the offensive can derive advantage from this weakness. But who does not see that this casual superiority of the attack is not to be carried to the credit of the offensive in general, for it is in reality created out of the superior relations of the defensive.

The fourth principle, the Assistance of the Theatre of War, is naturally an advantage on the side of the defensive. If the attacking army opens the campaign, it breaks away from its own theatre, and is thus weakened, that is, it leaves fortresses and depôts of all kinds behind it. The greater the sphere of operations which must be traversed, the more it will be weakened (by marches and garrisons); the army on the defensive continues to keep up its connection with everything, that is, it enjoys the support of its fortresses, is not weakened in any way, and is near to its sources of supply.

The support of the population as a fifth principle is not realised in every defence, for a defensive campaign may be carried on in the enemy’s country, but still this principle is only derived from the idea of the defensive, and applies to it in the majority of cases. Besides by this is meant chiefly, although not exclusively, the effect of calling out the last Reserves, and even of a national armament, the result of which is that all friction is diminished, and that all resources are sooner forthcoming and flow in more abundantly.

The campaign of 1812, gives as it were in a magnifying glass a very clear illustration of the effect of the means specified under principles 3 and 4. 500,000 men passed the Niemen, 120,000 fought at Borodino, and much fewer arrived at Moscow.

We may say that the effect itself of this stupendous attempt was so disastrous that even if the Russians had not assumed any offensive at all, they would still have been secure from any fresh attempt at invasion for a considerable time. It is true that with the exception of Sweden there is no country in Europe which is situated like Russia, but the efficient principle is always the same, the only distinction being in the greater or less degree of its strength.

If we add to the fourth and fifth principles, the consideration that these forces of the defensive belong to the original defensive, that is the defensive carried on in our own soil, and that they are much weaker if the defence takes place in an enemy’s country and is mixed up with an offensive undertaking, then from that there is a new disadvantage for the offensive, much the same as above, in respect to the third principle; for the offensive is just as little composed entirely of active elements, as the defensive of mere warding off blows; indeed every attack which does not lead directly to peace must inevitably end in the defensive.

Now, if all defensive elements which are brought into use in the attack are weakened by its nature, that is by belonging to the attack, then this must also be considered as a general disadvantage of the offensive.

This is far from being an idle piece of logical refinement, on the contrary we should rather say that in it lies the chief disadvantage of the offensive in general, and therefore from the very commencement of, as well as throughout every combination for a strategic attack, most particular attention ought to be directed to this point, that is to the defensive, which may follow, as we shall see more plainly when we come to the book on plans of campaigns.