Defense in depth was actually invented by the Germans in World War One: http://en.wikipedia.org/wiki/Trench_warfare#World_War_I:_trench_defensive_systems http:

Defense in depth was actually invented by the Germans in World War One: http://en.wikipedia.org/wiki/Trench_warfare#World_War_I:_trench_defensive_systems http://en.wikipedia.org/wiki/Trench_warfare#World_War_I:_tre... As were the concepts of Schwerpunkt and penetration. These are clearly described in, e.g., Rommel's book about his WW1 infantry operations (http://en.wikipedia.org/wiki/Infantry_Attacks http://en.wikipedia.org/wiki/Infantry_Attacks).