The enemy expected in April, 1917, a massive attack from the French air forces in the Aisne, and had taken measures to evade it. An order from the staff of the Seventh Army says that all flying units shall be given the alarm whenever a large number of French airplanes are sighted. The German machines must return to camp at once, refusing combat except on equal terms; and balloons must be lowered, or even pulled down to the ground. If, on the contrary, the German machines took the offensive, the order was that, at the hour determined upon, all available machines must rise together to a low altitude, and divide into two distinct fleets, the chasing units flying above the rest. These two fleets must then make for the point of attack, gaining height as they go, and must engage the enemy above the lines with the utmost energy, never giving up the pursuit until they reach the French lines, when the danger from anti-aircraft batteries becomes too great. From this it is evident that the preference of German Aviation for taking the offensive was not sufficient to induce it to offer battle above the enemy lines, and the tendency of the staff was to group squadrons into overpowering masses. The French had preceded their opponents in the way of technical progress, but the Germans made up for the inferiority, as usual, by method and system. The French were unrivaled for technical improvements, and the training of their pilots. Their new machine, the Spad, was a first-rate instrument, superior in strength, speed, and ease of control to the best Albatros, and the Germans knew that this inferiority must be obviated. All modern battles are thus preceded by technical rivalry. The preparation in factories, week after week, and month after month, ultimately results in living machinery which the staff uses as it pleases. Living machinery it is, but it is in appearance only that it seems to be independent of man. A battle is a collective work, to which each participant, from the General-in-chief to the road-mender behind the lines, brings his contribution. Colossal though the whole seems, perfect as the enormous machine seems to be, it would not work if there were not behind it a weak man made of poor flesh. A humble gunner, the anonymous defenders of a trench, a pilot who purges the air of the hostile presence, an observer who secures information in good time, some poor soldier who has no idea that his individual action was connected with the great drama, has occasionally brought about wonderful results--as a stone falling into a pool makes its presence felt to the remotest banks. Amidst the fighters on the Aisne, Guynemer was at his post in the Storks Escadrille. "All right! (sic) they tumble down," he wrote laconically to his family. There were indeed some five tumbling down: on May 25 he had surpassed all that had been done so far in aerial fights, bringing down four German machines in that one day. His notebook states the fact briefly: