which strategy moves are generally on a greater scale than those of tactics. If, therefore, an army posts itself at a distance of a mile from the sea coast or the banks of a great river, it leans strategically on these obstacles, for the enemy cannot make use of such a space as this to effect a strategic turning movement. Within its narrow limits he cannot adventure on marches miles in length, occupying days and weeks. On the other hand, in strategy, a lake of several miles in circumference is hardly to be looked upon as an obstacle; in its proceedings, a few miles to the right or left are not of much consequence. Fortresses will become strategic points d’appui, according as they are large, and afford a wide sphere of action for offensive combinations.
The disposition of the army in separate masses may be done with a view either to special objects and requirements, or to those of a general nature; here we can only speak of the latter.
The first general necessity is to push forward the advanced guard and the other troops required to watch the enemy.
The second is that, with very large armies, the reserves are usually placed several miles in rear, and consequently occupy a separate position.
Lastly, the covering of both wings of an army usually requires a separate disposition of particular corps.
By this covering it is not at all meant that a portion of the army is to be detached to defend the space round its wings, in order to prevent the enemy from approaching these weak points, as they are called: who would then defend the wings of these flanking corps? This kind of idea, which is so common, is complete nonsense. The wings of an army are in themselves not weak points of an army for this reason, that the enemy also has wings, and cannot menace ours without placing his own in jeopardy. It is only if circumstances are unequal, if the enemy’s army is larger than ours, if his lines of communication are more secure (see Lines