- The besieging, blockade, and investment of fortresses, generally increase as the army advances. This weakening influence alone acts so powerfully on the condition of the combatant force, that it may soon outweigh all the advantages gained. No doubt, in modern times, a system has been introduced of blockading places with a small number of troops, or of watching them with a still smaller number; and also the enemy must keep garrisons in them. Nevertheless, they remain a great element of security. The garrisons consist very often in half of people, who have taken no part in the war previously. Before those places which are situated near the line of communication, it is necessary for the assailant to leave a force at least double the strength of the garrison; and if it is desirable to lay formal siege to, or to starve out, one single considerable place, a small army is required for the purpose.
- The second cause, the taking up a theatre of war in the enemy’s country, increases necessarily with the advance, and if it does not further weaken the condition of the combatant force at the moment, it does so at all events in the long run.
We can only regard as our theatre of war, so much of the enemy’s country as we actually possess; that is to say, where we either have small corps in the field, or where we have left here and there strong garrisons in large towns, or stations along the roads, etc.; now, however small the garrisons may be which are detached, still they weaken the combatant force considerably. But this is the smallest evil.
Every army has strategic flanks, that is, the country which borders both sides of its lines of communications; the weakness of these parts is not sensibly felt as long as the enemy is similarly situated with respect to his. But that can only be the case as long as we are in our own country; as soon as we get into the enemy’s country, the weakness of these parts is felt very much, because the smallest enterprise promises some result