These schools of combat are connected with the _écoles de perfectionnement_ with which the pilot has finished. In the combat school he learns battle tactics, how to fight singly and in fleet formation, and how to extract himself from a too dangerous position. Trips are made in squadron formation and sham battles are effected with other escadrilles, as the smallest unit of an aërial fleet is called. For the first time the pilot is allowed to do fancy flying. He is taught how to loop the loop, slide on his wings or tail, go into corkscrews and, more important, to get out of them, and is encouraged to try new stunts. Finally the pilot is considered well enough trained to be sent to the reserve, where he waits his call to the front. At the reserve he flies to keep his hand in, practises on any new make of machine that happens to come out or that he may be put on in place of the Nieuport, and receives information regarding old and new makes of enemy airplanes. At last the pilot receives his call to the front, where he takes his place in some established or newly formed escadrille. He is given a new machine from the nearest airplane reserve centre, and he then begins his active service in the war, which, if he survives the course, is the best school of them all. CHAPTER V AGAINST ODDS Since the publication of previous editions of "Flying for France" we have obtained the following letters which add greatly to the interest and complete the record of McConnell's connection with the Lafayette Escadrille. _March 19, 1917._ DEAR PAUL: We are passing through some very interesting times. The boches are in full retreat, offering very little resistance to the English and French advance. The boches have systematically destroyed all the towns and villages abandoned. Where they haven't burned a house, they have made holes through the roofs with pickaxes. All the cross-roads are blown up at the junctions, and when the trees bordering the roads haven't been cut down, barricading the roads, they have been cut half way through so that when the wind blows they keep falling on the passing convoys. The inhabitants left in these villages are wild with delight and are giving the troops an inspiring reception. In one town the boches raped all the women before leaving, then locked them down cellar, and carried off all the young girls with them. We have been flying low, and watching the cavalry overrunning the country. The boches are retreating to very strongly fortified positions, where the advance is going to come up against a stone wall.