First published in 1922, written by a major-general, former chief of the ir staff. The introduction begins: " Since the earliest communities of human beings first struggled for supremacy and protection, the principles of warfare have remained unchanged. New methods have been evolved and adopted with the progress of science, but no discovery, save perhaps that of gunpowder, has done so much in so short a time to revolutionize the conduct of war as aviation, the youngest, yet destined perhaps to be the most effective fighting-arm. Yet to-day we are only on the threshold of our knowledge, and, striking as was the impetus given to every branch of aeronautics during the four years of war, its future power can only dimly be seen."