Through this difficulty, therefore, an army occupying a perpendicular position covers the nearest points on its line of communications for a distance of two or three marches, according to the strength of the army; but those nearest points are just those which are most in danger, as they are the nearest to the enemy.
On the other hand, in the case of a decidedly oblique position, no such part of the line of communication is covered; the smallest pressure, the most insignificant attempt on the part of the enemy, leads at once to a vulnerable point.
But now, what is it which determines the front of a position, if it is not just the direction perpendicular to the line of communication? The front of the enemy; but then, again, this may be equally as well supposed as dependent on our front. Here there is a reciprocal effect, for the origin of which we must search.
If we suppose the lines of communication of the assailant, a b , so situated with respect to those of the enemy, c d , that the two lines form a considerable angle with each other, it is evident that if the defensive wishes to take up a position at e , where the two lines intersect, the assailant from b , by the mere geometrical relation, could compel him to form front opposite to him, and thus to lay bare his communications. The case would be reversed if the defensive took up his position on this side of the point of junction, about d ; then the assailant must make front