At present, it must be remembered, the possibilities of an air-fleet are vague--all at least save one; and that is the utility of an airship or plane for scouting. The value of aircraft in this direction has been proved, not only in peace manœuvres but in war; but as to what destructive work an aeroplane can accomplish, or how machines will fight when they meet in mid-air, there is only theory for a guide. That an aircraft may carry explosives, and drop them with accuracy, is now an established fact; also that a machine-gun can be mounted upon a machine, and fired successfully at a target while the craft is in flight. But no country, as yet, has equipped itself with a squadron of fighting aeroplanes. For one thing, owing to the fact that powerful aviation motors are only just becoming available, craft are still small in size; and this limits them to the carrying of a light gun. What is wanted, and what will be built in time, is a large, armoured, high-speed craft, having more than one engine, carrying a crew, and being able to bear the load of a powerful gun. In war, had a Commander a squadron of such machines, he would use them for attacking an enemy’s supply stores and ammunition parks, for blowing up railway lines, and for harassing troops when they were on the march; and he would launch them, of course, when necessary against hostile aircraft which might approach his own lines. In the first instance, in the case of a great war, there will be a battle in the air; and how severe this will be must depend upon the strengths of the air-fleets opposed to each other. Command of the air, like command of the sea, will be all-important. If one Commander-in-Chief can cripple and disorganise his opponent’s air-fleet, it will be like blinding his enemy. He himself, still well served by his air-scouts, will note all the movements of his enemy; but this enemy, with an air fleet driven back, and most of its machines disabled, will be enveloped in what has been called “the fog of war”; he will glean no more as to his enemy’s tactics, that is to say, than can be obtained by cavalry or foot scouts. Not only the fighting aeroplanes, but the general equipment of the air-fleet, will play a part in the aerial battles of the future. Surprisingly intricate, and little known, is the organisation of a squadron of war machines. There must be trained mechanics in large numbers, and they must be driven from place to place in motors, according to the movements of the machines they serve. Then the aeroplanes, if necessary, must be packed on lorries and taken across country by road; and there must be portable sheds upon the landing grounds, in which they may be housed at night. There needs to be an equipment of spare machines also; and a number of travelling workshops with skilled engineers, which can be rushed from place to place for the repair of damaged craft. A sketch of one of these workshops on wheels, which are vital to the organisation, is seen in Fig. 89.