Though few activities of the Engineers were more important than the work of the Camouflage Section, and though certainly none was more picturesque or interesting, it is with some diffidence that I introduce the subject, for I am perfectly aware that American readers have been, to make use of a British colloquialism, “jolly well fed-up” on everything pertaining to camouflage. The point is, however, that they have been largely “fed-up” on misinformation. They have read hundreds of magazine articles and newspaper stories about fake trees and papier-maché horses and the like, but of the real work of the Camouflage Corps—which, as an American general remarked, was “as practical as machine-guns and as necessary as ammunition”—they have heretofore been permitted, for quite obvious reasons, to know next to nothing. Certain camouflage operations on the American Front were of such vital importance to the success of our armies that, far from acquainting the public with them, they were veiled in the profoundest mystery. Military camouflage is a development of the Great War and has, therefore, no history and little literature. It differs from the purely scientific work of engineering, which has few variants and in which nearly all problems can be worked out by formula, in that it has countless variants of light, color, and position, and each problem of concealment is an individual one. Upon the entry of the United States into the war, much study was devoted to French and British camouflage methods, both in the factory and in the field. The British, it was found, did nothing without the most careful scientific investigation, which included aerophotography of all materials, while the more careless and temperamental French relied rather on their innate artistic sense of form and color. By combining the best features of both systems and strongly tincturing them with American energy, ingenuity, and manufacturing methods, our Camouflage Service soon came to be recognized as the best equipped and most efficient in the Allied Armies. At Dijon, in the Department of the Haute-Marne, we established a huge plant, known as the Central Camouflage Factory, where a hundred soldiers and some nine hundred Frenchwomen were employed in the production of materials, while at the Army Camouflage School of Fort St. Menge, near Langres, practical instruction was given in the use of these materials in the field.