I was watching a history documentary about D-Day when it was mentioned that the new German Panzer V excelled on the eastern front since it was perfect for "mobile defence" which the documentary mentioned was "the last hope for the wehrmacht" on the eastern front. What was this mobile defence? How was it conducted? What strategical defence ideas did the Wehrmacht adopt against the red army aside from the designated fortress ideas?
What strategical defence ideas did the Wehrmacht adopt against the red army aside from the designated fortress ideas?
The reference is being made to the 'elastic' strategic defense being conducted by Manstein between the space of time between the defeat at Stalingrad and the defeat at Kursk. The principle of Elastic Defense would remain well after 1943, but it would never be conducted with such power or skill afterwards; and the introduction of the Panther is largely transitory. In this regard the documentary is missing the point completely. Panzer Vs equipped the Panzer Brigades that took part in these 'fire brigade' defensive actions, but they were far from the key to their successes; in fact, by the time the Panther was in service, the fire brigades could do no nothing past local counterattacks, really.
During the aforementioned 42-43 era of elastic defense, Manstein counterattacked with entire corps; the counterattacks were large, co-ordinated and very much capitalized on the tactical edge the Germans still possessed at that time. The result would often be the destruction of several assaulting RKKA Corps, or even Armies, with little relative loss in men or material for the Germans. The principle was not gaining the Germans any ground, yes, but it was preserving their forces and thus allowing them to grow, rather than deplete.
The reason the 'elastic defense' was so important in Manstein's thinking is because of the disaster wrought by having foot and horse-laden formations attempt to fall back from the infinitely more mechanized RKKA in the event of a breakthrough; it would not happen. Rather than keep what few Panzer divisions Army Group South had with their repsective formations, they were concentrated into Panzer Corps, such as Hausser's SS Panzer Corps, and used to bludgeon back breakthroughs before the Soviets could create larger victories out of local successes. It was a tacit acknowledgement that (1) the Germans were incapable of holding the front and were stretched far too thin and (2) they were in reality (and at large) a rather backwards, unmechanized army in relation to their foes on either front.* Manstein therefore sought to keep what few mobile formations he had concentrated and ready to counterattack, rather than waste them fighting in local area defenses. As the infantry fell back, the mobile formations would roar forwards, smashing or enveloping their pursuers before a retreat became a rout. Hence the term 'elastic defense'; rather than break, the line would stretch, then rebound.
*I highly recommend you read "Mechanized Juggernaut or Military Anachronism?: Horses and the German Army of World War II " by DiNardo, which illustrates just how few units in the German army were capable of mobile operations.
On top of the below answer I'd recommend the book Panzer Battles by Maj Gen F W von Mellenthin on the use of German Panzer forces in the Soviet Union. I always recommend this before the more popular work "Panzer Leader" by Guderian. Von Mellenthin was a field commander as opposed to Guderian who was a Staff Officer, so the first lived it from the front line.
Von Mellenthin addresses the mobile warfare of the beginning and the mobile defensive warfare once they realize how difficult was to contain Soviet waves once Germany lost the initiative.