In addition to this provision for the wants of an army in its advance into hostile country, the safeguarding of the troops against the risk of their becoming a band of demoralized marauders, wandering over a wide area to seek and appropriate food whenever they can find it—as was the case, for instance, in the Napoleonic wars—the maintenance of discipline and the continued usefulness of the troops as a concentrated body for the military purposes in view being further assured when both men and leaders are relieved of anxiety as to the continuance of their supplies.
The conduct of war at a great distance from the base by reason of the facilities offered for the forwarding alike of troops, reinforcements, supplies and military materials, the value of even a single line of railway in the achievement of this purpose having been incontestably established.
Defence of frontiers by strategical railways which may, also, become available for general use.
Investment of cities or fortresses in occupied territory when, owing to the lack or the deficiency of food supplies in the surrounding country, the troops engaged are mainly if not entirely dependent on those brought to them by rail from their own base.[79]
Victualling of cities before, and their revictualling after, investment.[80]
Extension of lines of communication by means of quickly-constructed narrow-gauge siege railways to be operated by motor traction, animal power, or otherwise, including therein trench tramways for (a) removal of wounded men from the trenches; (b) transport of siege guns to trenches; and (c) supplying ammunition to battery.
Transport of heavy siege guns, mortars, ammunition and other materials of a size or weight that would render impracticable their conveyance, whether singly or in the aggregate, along ordinary roads, the railway offering, in this respect, facilities for ponderous transport comparable to those of the steamship, with the further advantage of being able, in most instances, to take the guns, etc., to the spot or to the locality where they are wanted.
Material aid given to expeditions to countries otherwise devoid of means of communication, by the construction of military railways.
Employment of armoured trains which, apart from their usefulness in defending railways against attack, may, as movable fortresses, render important service in the operations against the enemy.