On War → ↑ Book IV: The Attack
Book IV, Chapter IV. Decreasing Force of the Attack
This is one of the principal points in strategy: on its right valuation in the concrete, depends our being able to judge correctly what we are able to do.
The decrease of absolute power arises—
-
Through the object of the attack, the occupation of the enemy’s country; this generally commences first after the first decision, but the attack does not cease upon the first decision.
-
Through the necessity imposed on the attacking army to guard the country in its rear, in order to preserve its line of communication and means of subsistence.
-
Through losses in action and through sickness.
-
Distance of the various depôts of supplies and reinforcements.
-
Sieges and blockades of fortresses.
-
Relaxation of efforts.
-
Secession of allies.
But frequently, in opposition to these weakening causes, there may be many others which contribute to strengthen the attack. It is clear, at all events, that a net result can only be obtained by comparing these different quantities; thus, for example, the weakening of the attack may be partly or completely compensated, or even surpassed by the weakening of the defensive. This last is a case which rarely happens; we cannot always bring into the comparison any more forces than those in the immediate front or at decisive points, not the whole of the forces in the field.—Different examples: The French in Austria and Prussia, in Russia; the allies in France, the French in Spain.