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 every where 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. The army in the enemy’s country takes under its protection the organisation which, as it advances, it necessarily introduces to form its lines of communication; and in general, inasmuch as terror, and the presence of an enemy’s army in the country invests these measures in the eyes of the inhabitants with all the weight of unalterable necessity, the inhabitants may even be brought to regard them as an alleviation of the evils inseparable from war. Small garrisons left behind in different places