y means of aerial photography they furnished
exact knowledge of the ground and of the enemy's defenses, thus
preceding the execution of military operations. They regulated artillery
fire, followed the program laid down for the destruction of the enemy,
and supplied such information as was necessary to set the time for the
attack. They then accompanied the infantry in the attack, observed its
progress, located the conquered positions, revealed the situation of the
enemy's new lines, betrayed his defensive works, and announced his
reinforcements and his counter-attacks. They were the conducting wire
between the command, the artillery, and the troops, and everybody felt
them to be sure and faithful allies, for they were able to see and know,
to speak and warn. But the air forces, during all their useful missions,
were themselves in need of protection, and there must be no enemy
airplanes about if they were to make their observations in security. But
how to rid them of these enemies, and render the latter incapable of
harm? Here the air cavalry, the airplanes built for distant scouting and
combats, intervened. The safety of observation machines could only be
insured by long-distance protection, that is to say, by aerial patrols
taking the offensive, not by a solitary guard, too often disappointing,
and ineffective against a resolute adversary. Their safety near to the
army could be guaranteed only by carrying the aerial struggle over into
the enemy's lines and preventing all raids upon our own. The groups
belonging to our fighting escadrilles on both banks of the Somme
achieved this result.

The one-seated Nieuport, rapid, easily managed, with high ascensional
speed, and capable, by its solid construction and air-piercing power, of
diving from a height upon an enemy and falling upon him like a bird of
prey, was then the chasing airplane _par excellence_, and remained so
until the appearance of the terrible Spad, which made its _debut_ in the
course of the Somme campaign, Guynemer and Corporal Sauvage piloting the
first two of these machines in early September, 1916. They were armed
with machine-guns, firing forward, and invariably connected with the
direction of the machine's motion. The Spad is an extraordinary
instrument of attack, but its defense lies only in its capacity for
rapid displacement and the swiftness of its evolutions. Its rear is
badly exposed: its field of visibility is very limited at the sides, and
object