I have expressed a hope that the chapters and letters will suggest a rough impression of work done by R.F.C. pilots and observers in France. A complete impression they could not suggest, any more than the work of a Brigade-Major could be regarded as representative of that of the General Staff. The Flying-Corps-in-the-Field is an organisation great in numbers and varied in functions. Many separate duties are allotted to it, and each separate squadron, according to its type of machine, confines itself to two or three of these tasks. The book, then, deals only with the squadron to which I belonged last year, and it does not pretend to be descriptive of the Flying Corps as a whole. Ours was a crack squadron in its day, and, as General Brancker has mentioned in his Introduction, it held a melancholy record in the number of its losses. Umpty's Squadron's casualties during August, September, and October of 1916 still constitute a record for the casualties of any one flying squadron during any three months since the war began. Once eleven of our machines were posted as "missing" in the space of two days--another circumstance which has fortunately never yet been equalled in R.F.C. history. It was a squadron that possessed excellent pilots, excellent achievements, and the herewith testimonial in a letter found on a captured German airman, with reference to the machine of which we then had the Flying Corps monopoly: "The most-to-be-feared of British machines is the S----." Our duties were long reconnaissance, offensive patrols around German air country, occasional escort for bombing craft, and occasional photography. I have but touched upon other branches of army aeronautics; though often, when we passed different types of machine, I would compare their job to ours and wonder if it were more pleasant. Thousands of feet below us, for example, were the artillery craft, which darted backward and forward across the lines as from their height of vantage they ranged and registered for the guns. On push days these same buses were to be seen lower still, well within range of machine-gun bullets from the ground, as they crawled and nosed over the line of advance and kept intelligent contact between far-ahead attacking infantry and the rear. Above the tangled network of enemy defences roved the line photography machines, which provided the Staff with accurate survey maps of the Boche defences. Parties of bombers headed eastward, their lower wings laden with eggs for delivery at some factory, aerodrome, headquarter, railway junction, or ammunition dump. Dotted everywhere, singly or in formations of two, three, four, or six, were those aristocrats of the air, the single-seater fighting scouts. These were envied for their advantages. They were comparatively fast, they could turn, climb, and stunt better and quicker than any two-seater, and their petrol-tanks held barely enough for two hours, so that their shows were soon completed.