3. That from the moment the assailant enters the enemy’s territory, there is a loss of provinces to the defence, consequently of the sources of new military forces.
4. That the advancing army gains a portion of those resources, in other words, gains the advantage of living at the expense of the enemy.
5. The loss of internal organisation and of the regular action of everything on the side of the enemy.
6. That the allies of the enemy secede from him, and others join the conqueror.
7. Lastly, the discouragement of the enemy who lets the arms, in some measure, drop out of his hands.
The causes of decrease of strength in an army advancing, are:
1. That it is compelled to lay siege to the enemy’s fortresses, to blockade them or observe them; or that the enemy, who did the same before the victory, in his retreat draws in these corps on his main body.
2. That from the moment the assailant enters the enemy’s territory, the nature of the theatre of war is changed; it becomes hostile; we must occupy it, for we cannot call any portion our own beyond what is in actual occupation, and yet it everywhere presents difficulties to the whole machine, which must necessarily tend to weaken its effects.
3. That we are removing further away from our resources, whilst the enemy is drawing nearer to his; this causes a delay in the replacement of expended power.
4. That the danger which threatens the state, rouses other powers to its protection.