[Footnote 18: The romantic circumstances under which he escaped in
February, 1918, are well known.]

The Maurice Farman and Caudron airplanes were used for observation. The
Voisin machines, strong but slower, were more especially utilized for
bombardments, which began to be carried out by organized expeditions.
The famous raids on the Ludwigshafen factories and the Karlsruhe railway
station occurred in June, 1915. It was at the battle of Artois (May and
June, 1915) that aviation for the first time constituted a branch of the
army; and the work was chiefly done by the escadrilles belonging to the
army corps, which rendered very considerable services as scouts and in
aërial photography and destructive fire. But as an enemy chaser, the
airplane was still regarded with much distrust and incredulity. Some
said it was useless; was it not sufficient that the airplanes of the
army corps and those for bombardments could defend themselves? Others of
less extreme opinions thought it should be limited to the part of
protector. This opposition was overcome by the sudden development of the
German enemy-chasing airplanes after July, 1915, subsequent to our raids
on Ludwigshafen and Karlsruhe, which aroused furious anger in Germany.

In the beginning the belligerent nations had collected the most
heterogeneous group of all the airplane models then available. But the
methodical Germans, without delay, supplied their constructors with
definite types of machines in order to make their escadrilles
harmonious. At that time they used monoplanes for reconnaissances,
without any special arrangement for carrying arms, and incapable of
carrying heavy weights; and biplanes for observation, unarmed, and
possessing only a makeshift contrivance for launching bombs. The
machines of both these series were two-seated, with the passenger in
front. These were Albatros, Aviatiks, Eulers, Rumplers, and Gothas.