Perhaps foreshadowing the late war developments of such German tanks as the Maus and the E.100 during World War Two and the folly (though, from a technical and engineering standpoint, valuable) of such efforts when the assets, money, and the time could be better spent on proven arms to support the war, the K-Wagen was to World War One German armor projects what the Maus and E.100 was to World War Two German armor projects.
In early 1917, the Chief of Motor Vehicles of the War Ministry placed the contract for the construction of the K-Wagen. The specifications of the contract called for a tank able to cross a trench at least 4 meters wide, have front and side armor up to 3cm thick, mount one to two cannon of 5cm to 7cm in caliber, mount four machine guns, mount two flamethrowers, be powered by a motor(s) developing 400hp, have an 18 man crew, and be able to be broken down into 30 ton loads for transport.
In committee discussions over the K-Wagen, much criticism was put forward over the impracticality of the design, both in the specifications and the reality of its deployment and success in the field. These voices were ignored and on June 28, 1917, the order for ten K-Wagens to be built was issued. And to top it off, the OHL ordered that the projected construction time of one year be cut to eight months.
From the start, the design ran into trouble. The designers had nothing to work from…they had to build a tank practically from the ground up. All new building techniques had to be fashioned and implemented and nearly all the components had to be made from scratch. Where possible, shortcuts were found such as the tracking which was adapted from power shovel machines. But things such as gearing and the clutch assembly all had to be made to specifications. Contracts were given out to the Riebe Ball Bearing Works in Berlin-Weissensee and the Waggonfabrik Wegmann in Kassel to build five K-Wagens each. As the two companies got to work, problems arose at every corner.
It was found very quickly that the original call for a 400hp engine arrangement was totally inadequate to grant the K-Wagen useful locomotion. Instead, two Daimler 6-cylinder marine engines were used, each engine developing 650hp. These engines were to give the K-Wagen a speed of 5mph (which is probably the road speed). Fuel tankage was 3,000 liters and to what range this would have allowed the K-Wagen to travel is not known. The weight of the K-Wagen had crept up to about 150 tons from its original 140 tons. By shortening the vehicle, it was speculated that the weight could be brought down to 120 tons. The original crew size of 18 was found to be too little to man the tank and it was increased to 22.
For armaments, Idstein Fortress provided 7.7cm cannon for the K-Wagens. These were mounted in socket mantlets very similar to the 5.7cm cannon on the A7V. The K-Wagen was armed with four of these 7.7cm cannon and the original call for four machine guns (no doubt Maxim 08/15s) increased to seven, the flamethrowers apparently having been deleted. Total rounds carried for the cannons was 8,000 (mix not known) and for the machine guns, one can assume over 15,000 rounds were on-board.
For armor, the specifications for 3cm of protection was met. Though, whether this armor thickness was maintained in all of the K-Wagen’s sections is not known as well as if this armor was of the hardened or unhardened type.
Overall, the K-Wagen resembled a long shoe-box. It was, vaguely, rhomboidal in the sense that the tracks went over the top of the tank. The ends of the tank were rounded and didn’t have the point the British tanks had. The K-Wagen’s tracks benefited from armor protection in that they ran up under the the roof armor plating and sported some measure of defense from the front and rear armor plates. Overall, the K-Wagen had very little riveting, the armored hull’s sections being apparently made in whole units. Attached to the side of the box hull were the sponsons. Unlike the movable (and in some cases, removable) sponsons of the British tanks, these were bolted to the hull. In a bulge in the sponson were mounted two 7.7cm cannon. One cannon faced forward while the other faced towards the back. Situated between the cannon was a machinegun. At the rear of the sponson was another, rear firing, machinegun. At the front of the tank, separated from the fighting compartment by a bulkhead, was to be found the two driver stations and three machine gun positions (one gun faced forward, the other two facing the sides). Approximately in the middle of the fighting compartment was a raised platform where the commander and an artillery officer sat, looking out thru a raised, cylindrical cupola on the top of the K-Wagen. Positioned in the front of the engine compartment was the signalman (whose duties were no doubt similar to those of the A7V signalman). Two mechanics were carried on-board to service the two engines (and probably assist in assembling the K-Wagen for action after transport). Behind the engine compartment, in the rear of the tank, was the gearbox assembly. Venting was provided by louvers on the top of the sponsons while the dual exhaust stacks were mounted on the roof a bit behind the cupola. For vision slits, the K-Wagen has a surprising lack of them. Aside from the ones in the cupola (which are dotted around the cupola to grant all around sight), the only other vision slits can be seen on the sponson, between the cannon. The front, where the drivers are, seems to have no vision ports at all! And since the driver stations were set back from the front of the tank, one wonders how they were to see where they were going. The K-Wagen’s dimensions were as follows: Length= 41ft.3in. (12.6m), Width= 19ft.6in. (5.9m), Height= 9ft.10in. (2.9m), Clearance= unknown.
As the troubled progress on the K-Wagen went on, the A7V had been deployed and the Germans had been on the receiving end of successful Allied employment of armor. All this seemed to grate on the war offices and doubts crept into their minds as to the value and practicality of the K-Wagen. This culminated in the Testing Department of Field Vehicles issuing a statement on October 18, 1917 that the only suitable deployment of the K-Wagen would be in positional warfare, i.e. static defenses, a pill box on tracks (something that the World War Two Jadgtiger was often deployed as).
The K-Wagen program slogged on thru technical problems and also from difficulties in getting parts and components from outside suppliers. However, the close of hostilities also brought to a close the K-Wagen project. Riebe Ball Bearing Works had one K-Wagen in the final stages of completion with a second one in a lesser state and sans engines. Wegmann had, in all this time, nearly finished one K-Wagen armored body.
The K-Wagen was a project which had little to gain in terms of a tank which would have found success on the field. In mobile warfare, it would have found itself at a supreme disadvantage. Its speed of 5mph, which is probably a road speed, would have dropped to a horrid rate overland. And with a weight of over 120 tons, it surely would have bogged down in the mire and soft earth of the battlefield, leaving it vulnerable to artillery, tank fire, and close assault. How strong the tracks were, given their civilian roots (recall they were from power shovel machines), might be called into question and that fouling and clogging of the upper gear would have been a serious problem. Its sloth-like speed would have been to its detriment against swifter tanks such as the cannon armed FT-17 and bold anti-tank infantry teams. And that this tank needed two drivers attests to the difficulty in handling the machine. If the problems with the A7V in terms of crew efficiency in action were difficult, it had to have been worse with the K-Wagen. Given that there seems to be no vision ports for the drivers, they would have had to rely on orders from the commander, passed thru to them via the signalman, as to where to drive. And with the location of the cupola, the commander had an even bigger dead angle to the front than with the A7V. Apparently, the artillery officer would have had the task of commanding the gunners. One can imagine the signalman would get quite a workout having to deliver orders from two officers. In terms of weapons, the K-Wagen can be considered the most heavily armed tank to have been built during the war. The performance of the 7.7cm cannon is not known but would probably have been more than capable of penetrating the armor of any Allied tank. The coverage of the machine guns would have been good with the only real blind spot being the direct rear of the tank. Armor-wise, the K-Wagen would have still had the edge in protection. Transportation of this tank posed a serious problem as can be seen in the fact that one of the requirements was that it was to be capable of being broken down into sections. Thus, this limits the tactical flexibility of the K-Wagen in that it could not be rapidly deployed and sent into action. And if there were bridges to be crossed, the K-Wagen would probably have had to have been broken down again, taken across, then reassembled. In static warfare, which, as was seen, was to be the suggested role of the K-Wagen, it might have proven a problem to deal with if deployed right. Its fire control would have improved as the commander wouldn’t have to worry about giving the drivers directions and could concentrate, along with the artillery officer, on target acquisition. However, like any other pill box, use of artillery and combined arms would have rendered it vulnerable, its only saving grace being that it might be able to move from spot to spot. From a technical standpoint, the K-Wagen was an interesting project, too little, too late in the war which was already lost. And even if it had taken the field, the K-Wagen would have fallen prey to the new generation of combat tanks such as the Mk. VIII “Liberty” heavy tank and the Medium B and C fast tanks.