Monday 15 August 2022

Surprises in the Snow

Trials of foreign materiel, including captured vehicles, were quite limited before the war. This had a lot to do with the technical condition of the vehicles that fell into the hands of the Red Army. As a rule, this condition was far from ideal, meaning that the scope of possible trials was limited. Full scale trials were rare. For example, the Pz.Kpfw.I Ausf.A tank captured in the fall of 1936 in Spain arrived more or less intact, and therefore could be used for many trials, including trials against various obstacles. It's hard to say that these trials were very useful since Soviet tanks of that era were already more than a match for this tank. The T-26 that fought against the Pz.Kpfw.I Ausf.A in Spain surpassed it in all parameters. Nevertheless, there was a certain value in these trials.

Pz.Kpfw.III Ausf.H tank "Isabella" during winter trials, January-March 1942.

The situation after the start of the Great Patriotic War was different. There were more trophies and more possibilities of repairing them. Initially captured vehicles were used for their primary purpose. They went into battle after being repaired. As a rule, the NIBT Proving Grounds received damaged tanks that were incapable of driving. Nevertheless, since multiples of tanks arrived, it was possible to restore some of them to fully working condition. Primarily, these were the Pz.Kpfw.III, Pz.Kpfw.IV, and Pz.Kpfw.38(t). The next step was obvious. The Pz.Kpfw.III and Pz.Kpfw.38(t) were chosen for trials. The first was the most numerous German tank in 1941-42, the second was interesting since unlike the LT vz. 35 this tank was not yet tested in the USSR. Interestingly enough, trials of the Pz.Kpfw.IV were later cancelled. This was because the proving grounds staff considered the Pz.Kpfw.III and IV to be very similar and there was no need to waste resources testing it. In general, the Red Army neglected the Pz.Kpfw.IV, since the Pz.Kpfw.III was considered more technically progressive. No one could have guessed that by 1943 the Pz.Kpfw.IV would become the Wehrmacht's main tank.

The first obstacle: a 5 meter wide and 3 meter deep trench.

The Pz.Kpfw.III was actually already tested, but these were summer trials of the Pz.Kpfw.III Ausf.G purchased in 1940. Unfortunately, the complete record of the trials did not survive, so there are many speculations about them. Winter trials were not held since the tank travelled between various factories where various components were studied. The NIBT Proving Grounds received several new Pz.Kpfw.III tanks in the summer of 1941, including one Pz.Kpfw.III Ausf.H with the personal name "Isabella". It is not known where this tank came from, but it arrived in running condition. Repairs were still needed and were conducted by proving grounds staff. The tank left with the proving grounds for Kazan in the fall of 1941. Ironically, it would be tested where German Grosstraktor medium tanks were tested 10 years prior.

The German tank spun its tracks helplessly when trying to climb. It did not have enough traction to get out of the trench.

The winter trials were not entirely ordinary. Their purpose was not to get the characteristics of the tank in the usual sense. The trials program required the testers to find out how the German Pz.Kpfw.III and IV medium tanks dealt with engineering obstacles. Matilda III, Valentine II, and T-34 tanks also went through trials. As for the Pz.Kpfw.IV, it was not used due to similar characteristics. Performance of the Pz.Kpfw.III would count for both. 

The T-34 could cross the trench even with just one fascine.

The first stage of the trials involved crossing anti-tank trenches. A trench 5 meters across and up to 3 meters deep was dug. Four fascines were used to make the crossing easier. The tank drove onto the fascines and had to climb out after. The Pz.Kpfw.III could not get out due to a lack of traction. The T-34 tank could do this easily, albeit with spurs on the tracks. Without fascines, none of the tanks could cross the trench.

The Pz.Kpfw.III's bad luck continued with the second trench. It could not climb out either.

A more complex trench was used in the second round. It was 7 meters wide and 3 meters deep with a steep side. None of the tanks could cross it. The question was, could the tanks escape from the trap? This was once again no problem for the T-34, but the Pz.Kpfw.III got stuck again. After the trials the second trench was modified. It was made symmetric, with even steeper sides. This made it a fatal trap for all tanks. As a result, it was recommended to dig 7 meter wide trenches in the most critical sections of the front and 5 meter wide ones on secondary sections.

The first line of obstacles: two layers of anti-tank hedgehogs made from 130x130 mm steel angle bars arranged in two rows.

Trials of anti-tank hedgehogs were more interesting. Different types of obstacles in different arrangements were used. The first trial was negotiation of anti-tank hedgehog #13 (130x130 mm) arranged in two rows. The obstacles were tied together and wooden stakes were dug into the ground between them.

The tank crushed the hedgehogs and stakes.

This was not a problem for the German tank. It accelerated in second gear from 25 meters away, easily tearing through the obstacle, smashing a stake. One hedgehog was broken and two more were damaged. This tore off one of the tank's return rollers, but it was not immobilized.

Second line of obstacles: the hedgehogs are arranged in three rows.

The second obstacle was made of hedgehogs assembled from 150x100 mm and 120x120 mm angle bars in three rows. The hedgehogs were not connected. This obstacle was also not a problem. The tank pushed the hedgehogs aside without a running start and moved on. The commission was generally sceptical about building hedgehogs from angle bars as they could be easily destroyed.

These hedgehogs were also not a problem.

The third obstacle was made of hedgehogs #20-22 built from channel bars arranged in two rows. An attempt to cross the obstacle from a running start failed. This time the hedgehog managed to withstand the German vehicle. It hung on the obstacle and had to reverse.

Anti-tank hedgehogs #20-22 built from channel bars.

The tank crossed the obstacle on the second try by pushing apart the hedgehogs not linked to one another. The commission recommended using anti-tank hedgehogs built from channel bars or I-beams as the most durable and effective types. Linking them together and also affixing them to stakes or dragon's teeth was also required.

The only type of obstacle that the German tank could not cross on the first try.

For context, analogous trials were performed with the KV-1 and T-34 tanks starting on March 18th 1942. Train rails were used to build the hedgehogs. The KV-1 could smash through them in third gear. The T-34 could punch through two rows of hedgehogs in second gear. This could be expected, as the Soviet tanks had a better power to weight ratio and were heavier.

The hedgehogs were not a problem for the T-34 and KV-1.

The last stage of the trials was an active obstacle. Major General L.Z. Kotlyar, the chief of the Red Army's engineering forces, ordered the development of a special mine that would strike at the belly of German tanks on January 9th 1942. On January 20th 1942 the 11th Army Defensive Fortifications Directorate presented two types of lever mines. Both had the same length (2280 mm) but were made of different materials: one was made of planks and the other of rods. In both cases, the mines could be built with readily available materials, as the mechanism was made of wood. The principle was simple. The tank drove up on the mine mechanism and the lever pressed the explosive charge against the hull, which then went off.

Lever anti-tank mine, the last participant of winter trials.

The Pz.Kpfw.III tank was also used in these trials. The mine was not armed, but trials showed that it went off flawlessly. The result was that the PRM (anti-tank level mine) was accepted into service with the Red Army. It was not specially produced. The PRM was built at front line workshops. Thankfully, there was no shortage of wood.

Trials showed that the mine worked flawlessly.

Instructions on building anti-tank obstacles were developed as a result of these trials. The winter trials also demonstrated that the T-34 could pass through obstacles much more easily than the Pz.Kpfw.III, which was not a surprise all things considered.

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