to its full capacity in order to carry armour that would be proof against modern fire.
The use of the armoured car is limited to the roads, although in some seasons in open countries it is possible to operate over large areas of terrain away from the roads. Obstacles can hinder the progress of cars to a certain extent, but with determined and skilful drivers, and well-trained crews, there are very few roads over which cars cannot be taken. In civilized warfare the maintenance of large armies necessitates roads being kept open for wheeled transport, and once the line formed by the fighting troops is overcome there is very great scope for the employment of armoured cars if placed under the control of a skilful and enterprising commander.
At the outbreak of the World War in 1914 several well-designed types of armoured cars were produced, but the enormous demands for motor transport on the part of all the combatants to equip their rapidly increasing forces prevented the production and development of armoured cars in sufficient numbers to do effective work at the beginning of the war. During the fighting in the autumn of 1914 there were many opportunities for their use, and a few naval cars and some small units did very useful work in France and Belgium, but when the armies on the western front settled down to trench warfare the blocking of the roads prevented the further effective use of armoured cars on that front. The armoured cars that had been made were then sent to the distant fields of operation in Egypt, Mesopotamia, East and South-West Africa, while the detachment of naval armoured cars that fought in Belgium were employed in Rumania and southern Russia, where they were almost the only representatives of the British army in those countries. During the periods in which the contending armies were stationary and gathering their forces for the decisive contest there was no scope for the armoured cars, owing to the shell-torn roads, trenches and barbed wire, but the value of the armoured protection, mobility and fire-power of the armoured car contained the basis of the idea which was to have considerable effect on the latter phases of the war. In the stationary warfare of trenches the deciding factors were machine-gun fire, wire and mud. The armoured car could withstand the first by its armour protection, and could return it on equal terms with its own machine-gun fire. If it could be made to cross mud and wire the attack could then meet the defence of trenches on more than equal terms. The best machine for crossing soft and broken ground at that time was the tractor with the endless steel belt, and by a compromise of the armoured car and the tractor the British tank was evolved (see Tanks).
Under peace conditions armoured cars form an essential part of most standing armies. As a means of policing the enormous areas in which the British army is responsible for keeping the peace the armoured car provides a unit which can be kept mobile, ready to move at the shortest notice, and can cover the greatest distances with the minimum fatigue and the maximum speed. It can only be exceeded in these respects by the aeroplane, but, unlike that machine, the armoured car unit can provide the armoured protection of a miniature mobile fort, equipped with machine-guns, searchlights, a plentiful supply of ammunition, food and water, that can hold its ground until a well-organized and well-equipped enemy has been assembled to meet it. In cases of civil disturbances, apart from armed rebellion, the armoured car provides a means by which the civil forces of the law can penetrate into the middle of a crowd in a way that would be impossible under ordinary conditions of police duty.
ARMOURED TRAINS.—In the earliest days of the application
of railways to war uses, the idea presented itself both to
inventors and to practical soldiers of utilizing the weight-carrying
capacity of the railway and the pulling power of the locomotive
for tactical as well as for strategic purposes. " Railroad
batteries " figured in the American Civil War, and in the war
of 1870; and armoured trains have appeared thereafter sporadically
in most wars. Their utility, though it was confined within
rather narrow limit?, was unquestionable until the development of mechanical road transport. Nowadays, however, in countries
where the rail system is sufficiently developed to give such
trains real freedom of movement there exists an even fuller
system of main roads on which armoured cars can operate,
and in the World War period the fighting train has only figured
in such theatres as those of the Russian civil wars, in which
roads fit for heavy traffic are as a rule rarer than railways. As
against the armoured car working on good roads the train must
always suffer from being limited to certain tracks which are very
easily interrupted by raids, air bombing, or artillery fire, and
in the future, as cars of the four-wheel drive or caterpillar types
improve, the freedom of movement of the armoured car cannot
but increase even in theatres of war in which roads are few.
Considered as a self-contained fighting unit, therefore, it is improbable that the armoured train will be of much practical
utility in the future.
On the other hand, the old " railroad battery " considered as a form of gun-mounting possessed, and more than ever now possesses, many intrinsic advantages over other forms of mounting heavy ordnance for field warfare. In the well-laid bed of a railway track, organized to distribute heavy strains equably, such mountings have their firing platform ready made, and the power of the locomotive gives heavy artillery a mobility that otherwise it would lack. In this form, then, the train represents the battery vehicles of horsed or motor artillery. The central member is the heavy truck carrying the gun, and the others are arranged for ammunition and for the accommodation of the gun personnel. Light armour is frequently used for the protection of the vehicles against shrapnel bullets, and in some cases the gun itself is provided with a shield. These railway mountings are referred to under Ordnance.
ARMOUR PLATE (see 2.578). The history of armour plate
during the years 1909–21 differs from that of most other mate-
rials used in warfare, inasmuch as the period of greatest progress
and activity occurred before the World War and was followed
by a period of rest amounting almost to stagnation. The actual
years of the war, which constituted a period of intensive culture
as regards guns, shell, airships, aeroplanes, tanks, etc., added
no stimulus to progress in the manufacture of armour plate.
The efforts of British shipbuilders were devoted to the building
of light, fast cruisers and destroyers for which there was urgent
and immediate need, rather than to heavily armed battleships
which would take three years to complete.
During the years immediately preceding the war, however, the manufacture of armour plate had made steady progress, and the improvement in quality was marked. There were no radical alterations such as the employment of a new alloy steel, or the introduction of a new process of manufacture; but in the application of scientific principles to the details of manufacture, and the various heat treatments through which the plate passes, immense improvements had been made and were apparent in the quality of the finished plate. In this connexion it can be recorded that a long series of trials have proved beyond doubt that British armour made immediately before the war was greatly superior in ballistic qualities to that manufactured in Germany, in spite of the fact that the process of armour-plate manufacture originally came from Germany. For example, a German 12-in. plate was found to be no better than a British 9-in. under the same test, while a German 10-in. plate was only equal to the British 8-in. The plates tested were taken from the ex-German battleship “Baden,” and are therefore thoroughly representative of the German product.
Table I. British and German Armour.
| Thickness of plate in ℔. per sq. in. | Index representing limiting velocity of penetration | |
| 320 ℔. armour 400 " 480 " 560 " | British 1,000 1,000 1,000 1,000 | German 940 less than 855 less than 835 915 |
In Table I the average limiting velocity of penetration for British plates is taken to be 1,000 ft. per second in each case;
