In addition to operating independently, cooperation between the various army branches - Verbundene Waffen - was another important characteristic of the Prussian/German army. This emphasis on cooperation is interesting because it is almost diametrically opposed to the independence needed by Auftragstaktik. How can you cooperate with other units when you are expected to operate independently? Verbundende Waffen is the doctrine that combines these two opposing doctrines into a powerful whole. Paper is patient and the reality of the battle field unruly, so the Prussian and German army invested a lot of time and energy to get this - sometimes unnatural - way of operating off the ground. But once they mastered this, it turned out to be an extremely powerful tool on the battle field. The structure the Prussians/Germans used was the Kampfgruppe.
The German army, like any army, was structured along functional lines and divided into branches such as infantry, cavalry, artillery, engineers, and so on. This division into specialized units contributes to the professionalism and quality of the individual parts, but can lead to a sub-optimization of the whole. The Prussians and Germans had a clear understanding of this, hence their adage of Verbundene Waffen. After all, the primary function of an army - fighting - requires a context-bound optimal mix of these functional units and the army organization that succeeds to field this has the edge on the battlefield. Cooperation was thus the central theme within the German army and this focus on cooperation was stimulated and practiced in the width and the depth of the organisation in order to make the type of fluid, mobile operations that were envisaged, possible.
Front units could combined be within minutes into these Kampfgruppen, that responded to the demands of the battlefield in that sector of the front at that moment. These Kampfgruppen made the Prussian / German army particularly 'agile' and resilient and contributed highly to the battlefield performance. And Kampfgruppen could strategically make the difference, as the case Kampfgruppe Spindler showes at Arnhem in September 1944.
“In addition there was the astonishing flexibility in the chain of command which permitted the instantaneous welding together of the most heterogeneous units, from all arms, into effective battlegroups.”
British Field Marshal Alexander
Kampfgruppen could consist of a few hunderd men up to into the thousands, and could exist for a day or one or two weeks. In the end they were dissolved and the units returned to their 'mother' division. This focus on cooperation prevented units from desintegrating under pressure and keep on fighting because there still was unit cohesion. The allies (and historians and moviemakers) often interpretated and interpretate this as fanatism, but it for the men in question there was no reason to give up the fight.
Arnhem also shows the ease with which German units fused together into Kampfgruppen. Here an officer of probably Waffen SS Division Hohenstaufen takes charge of a unit consisting of troops of the Luftwaffe and Kriegsmarine, an exotic combination at least.