But there were further reasons, exterior to herself, to be found in the particular condition of the military problem.

In all campaigns, and especially in those which are defensive in character, as this then was, it is an accepted principle that the front of operations should be advanced, or, in case of retreat, should be maintained, as far forward as is possible consistent with general considerations of safety.

Prominent among the latter is always the securing of the lines of communication, by which alone supplies and reinforcements can be received, or {p.184} further retreat made in case of necessity.

By detaining the enemy in such an advanced position, security--partial or total--is obtained for the various interests in the rear, whether public or private.

The question of such detention, however, if to be effected by an inferior army, is difficult and complicated; for which reason, as well as because of other disadvantages inherent in inferiority, a defensive campaign really great--great, that is, in a military sense--makes the highest demand upon military skill.
It was the defensive stage of Napoleon's Italian campaign of 1796 that illustrated his greatness, even more conspicuously than the offensive movements which preceded it, extraordinary exhibitions though they were of his military genius; and the same distinction attends his resistance of the allied invasion in 1814.
In certain conditions of country, in certain relative degrees of numerical strength, under certain political conditions--for it is a grave mistake to think that military and political considerations can be dissevered practically, as they can logically--an inferior force can contest {p.185} step by step, content to delay only, not to arrest.