tolerably sure of a victory, or if the nature of the country does not offer some most decisive reason to give battle in a position further forward—in all these cases we say when a fortress is situated near at hand and capable of defence, the defender should by all means withdraw at once behind it, and let the decision take place on this side, consequently with its co-operation. If he takes up his position so close to the fortress that the assailant can neither form the siege of nor blockade the place without first driving him off, he places the assailant under the necessity of attacking him, the defender, in his position. To us, therefore, of all defensive measures in a critical situation, none appears so simple and efficacious as the choice of a good position near to and behind a strong fortress.
At the same time, the question would wear a different aspect if the fortress was situated far back; for then it would be necessary to abandon a considerable part of our theatre of war, a sacrifice which, as we know, should not be made unless in a case of great urgency. In such a case the measure would bear more resemblance to a retreat into the interior of the country.
Another condition is, the fitness of the place for defence. It is well known that there are fortified places, especially large ones, which are not fit to be brought into contact with an enemy’s army, because they could not resist the sudden assault of a powerful force. In this case, our position must at all events be so close behind that we could support the garrison.
Lastly, the retreat into the interior of the country is only a natural resource under the following circumstances:—
a, when owing to the physical and moral relation in which we stand as respects the enemy, the idea of a successful resistance on the frontier or near it cannot be entertained.
b, when it is a principal object to gain time.