The first necessity of our plane production was for training purposes, of which we had hitherto made only those for primary instruction. Deliveries of improved models of these planes began in June, 1917, but those for advanced instruction required longer for their manufacture. At the end of hostilities more than 8,000 had been provided. In a year and a half an airplane manufacturing industry had been developed and a total of nearly 12,000 planes had been produced, together with a large quantity of spare parts of every type, and there were orders outstanding for service planes to be ready for early delivery aggregating a value of $125,000,000. In addition to the means for training flying men, there had to be provided a series of schools for the training of the non-flying officers and men of the Air Service. Engineer officers to direct the upkeep of the equipment, supply officers to keep it on hand in sufficient quantities, and adjutants to have charge of the records were all essential to the Air Service. All had to have a certain amount of training and, at first, schools were provided for each of these special needs. Schools or courses of instruction had also to be instituted for aerial photography, for radio work, for armament and compass officers. Another series of schools for mechanics was necessary in order to train men for the fifty or more trades necessary in the repair and supply shops of flying fields. Much of the work was new to American mechanics and demanded the greatest skill, care and delicacy of execution and in schools for this purpose intensive training was given to them as rapidly as they could be secured. Many of these mechanics had also to be sent overseas, at the request of our co-belligerents, for service in their factories and flying fields, in addition to those who went to work in our own flying fields in France. CHAPTER XVII TRAINING THE MEN Great as was the problem this country faced in the spring of 1917 on the material side of the creation of a new branch of warfare in the American Army--the construction of fields and planes, the development of industries and the procuring of skilled labor--even greater was the problem of working out a new system of training. We are accustomed to the creation of new industries and certain nuclei already existed around which this new one could be formed. We had trained a few civilians and soldiers to fly, but we had not trained an aviator, and had no means of training even one, for usefulness on the battle front. And we were urged to send overseas at the earliest possible moment 5,000 aviators schooled in the developments and the specialties which nearly three years of the hot-house growth of war aeronautics had brought about.