The principles of conduct of war and conduct of combat as expounded in this book by Field Marshal General Ritter Wilhelm von Leeb were written only a few years before the present war. Von Leeb realistically and meticulously examined and re-examined the existing conceptions of defense to analyze what of value remained from World War I. He originally published his theories in the Milit?rwissenschaftliche Rundschau ("The Scientific Military Review") of the German War Office. They were later issued in book form, under the title Die Abwehr, in Berlin in 1938, and appear for the first time in English translation in this work. In his DEFENSE von Leeb, as a military thinker and scientist, comparable to any of the outstanding authorities of the old German army - Schlieffen, Falkenhayn, Groner, Seeckt, etc. - offered his government a plan for the next war in which Germany might be engaged. It is estimated by competent judges as probably "the most important piece of research in the field of strategy and tactics in modern warfare that has appeared in a decade."