Book excerpt: In this Research Survey, Major Timothy A. Wray provides an excellent survey of the intricacies of employing defensive tactics against a powerful opponent. Using after-action reports, unit war diaries, and other primary materials, Major Wray analyzes the doctrine and tactics that the Germans used on the Eastern Front during World War II.At the end of World War I, the Germans adopted the elastic defense in depth and continued to use it as their basic doctrine through the end of World War II. However, because of limitations caused by difficult terrain, severe weather, manpower and supply shortages, Soviet tactics, and Hitler's order to stand fast, German commanders were unable to implement the Elastic Defense in its true form. Even so, innovative and resourceful unit commanders were able to adapt to the harsh realities of combat and improvise defensive methods that saved the German armies from complete annihilation.