Lines of Communication

The roads which lead from the position of an army to those points in its rear where its depots of supply and means of recruiting and refitting its forces are principally united, and which it also in all ordinary cases chooses for its retreat, have a double signification; in the first place, they are its lines of communication for the constant nourishment of the combatant force, and next they are roads of retreat.

We have said in the preceding chapter, that, although according to the present system of subsistence, an army is chiefly fed from the district in which it is operating, it must still be looked upon as forming a whole with its base. The lines of communication belong to this whole; they form the connection between the army and its base, and are to be considered as so many great vital arteries. Supplies of every kind, convoys of munitions, detachments moving backwards and forwards, posts, orderlies, hospitals, depots, reserves of stores, agents of administration, all these objects are constantly making use of these roads, and the total value of these services is of the utmost importance to the army.

These great channels of life must therefore neither be permanently severed, nor must they be of too great length, or beset with difficulties, because there is always a loss of strength on a long road, which tends to weaken the condition of an army.

By their second purpose, that is as lines of retreat, they constitute in a real sense the strategic rear of the army.

For both purposes the value of these roads depends on their length, their number, their situation, that is their general direction, and their direction specially as regards the army, their nature as roads, difficulties of ground, the political relations and feeling of local population, and lastly, on the protection they derive from fortresses or natural obstacles in the country.

But all the roads which lead from the point occupied by an army to its sources of existence and power, are not on that account necessarily lines of communication for that army. They may no doubt be used for that purpose, and may be considered as supplementary of the system of communication, but that system is confined to the lines regularly prepared for the purpose. Only those roads on which magazines, hospitals, stations, posts for despatches and letters are organised under commandants with police and garrisons, can be looked upon as real lines of communication. But here a very important difference between our own and the enemy’s army makes its appearance, one which is often overlooked. An army, even in its own country, has its prepared lines of communication, but it is not completely limited to them, and can in case of need change its line, taking some other which presents itself, for it is everywhere at home, has officials in authority, and the friendly feeling of the people. Therefore, although other roads may not be as good as those at first selected there is nothing to prevent their being used, and the use of them is not to be regarded as impossible in case the army is turned and obliged to change its front. An army in an enemy’s country on the contrary can as a rule only look upon those roads as lines of communication upon which it has advanced; and hence arises through small and almost invisible causes a great difference in operating.
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