Its advantage was evident from the first day of the Somme offensive, not only in mechanical power, but in a method which cooerdinated and increased its efforts under a single command.  Though this arm of the service was in continuous evolution, more subject than any other to the modifications of the war, and the most susceptible of all to progress and improvement, it had nevertheless finished its trial stages and acquired full development as connecting agent for all the other arms, whom it supplied with information.  Serving at first for strategic reconnaissance, and then almost exclusively for regulating artillery fire, the aerial forces now performed complex and efficient service for every branch of the army.  By 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