Again the barrage tactics are extremely useful in the prevention of secrets being divulged to the enemy. Certain important movements, such as the moving up of reinforcements, are taking place in a certain part of the line, and to keep the enemy from knowledge of the fact _squadrillas_ of battle-planes are sent up to bar the way to the enemy scouts, and nothing can penetrate the screen of the _avions_. Thus it has so happened that, thanks to the barrage system, the enemy has been without definite news of the Allies’ movements during twenty-four hours. But let it be remembered that the aerial dam implies the mastery of the air, as important to the Allies as the mastery of the seas: indeed, one could establish a very close analogy between the two. The mastery of the air—the complete mastery—would have meant the finish of the war, the absolute victory for that side which possessed it. And the aerial fleet must consist of aeroplanes, not Zeppelins. For after all the Zeppelins failed miserably either in their bombardment of England or their assault upon French towns. True they have taken toll of a certain number of innocent lives in England, but an infinitesimal number in comparison with the holocaust caused by a terrestrial bombardment. Cumbersome, unwieldy, unable to operate except in a fog, the Zeppelin was comparatively ineffectual as an engine of war, and would not have been employed by the Germans except to prevent the public exposure of a mistaken policy. Six aeroplanes could effect more damage than one Zeppelin, whose radius of action is circumscribed by the fact that it has to carry vast weight for a long journey, that it is expensive to build, and consumes immense quantities of fuel _en route_; that it is almost as dangerous to itself as to the enemy on account of its vulnerability from cannon and from high winds, and moreover it is constantly exposed to attack from the upper strata of air by the aeroplane which swoops down upon it with the speed of the eagle, and against which the Zeppelin has no defence. No, it is the aeroplane that has come to stay, and a very prominent airman—a man who bears a household name in aeronautics—declared to me that the side which could furnish ten thousand aeroplanes with the airmen to mount them would win the war. For if aerial bombardment had, up to that moment, taken very little place in the hostilities it was because it was on so small a scale. Very little effect was to be obtained by sending half a dozen apparati over a town—it is true that in some of the French raids over German towns there were as many as thirty machines employed, but this was the great exception. It is easy to conjure up the effect of a gigantic bombardment—a shower of metal from the sky—rained everywhere upon the enemy troops on the march, upon the enemy convoys in the rear, upon his stores and magazines, upon his bridges and railways. Such a bombardment, if it could be continued systematically for long enough,