On the German Art of War: Truppenf++hrung: German Army Manual for Unit Command in World War II (Art of War (Stackpole Books))

Truppenführung ("unit command") served as the basic manual for the German Army from 1934 until the end of World War II and laid the doctrinal groundwork for blitzkrieg and the early victories of Hitler's armies. Reading it is as close to getting inside the minds behind the Third Reich's war machine as you are likely to get.