The PzIII, the main German tank for the first half of WWII, was at the same time its most problematic tank. Even though the PzII also had problems with its suspension, it was only seriously redesigned once. The PzIII, on the other hand, used five (!) different types of suspension, all of which went into production. Today, we will focus on the "intermediate" PzIII Ausf. B, C, and D. Even though none of these tanks were made in large numbers, they managed to see battle, and some of them remained on the front lines for a long time.
The first experimental Z.W. prototype, indexed Z.W.1, was completed in August of 1935. Sadly, no details on the trials of the Z.W.1 have been found. However, something was clearly wrong with the suspension.
The coil spring suspension that was first tried on the Rheinmetall Leichttraktor had 4 road wheels per side. Trials of the suspension on this tank were likely successful, as the same suspension was used on the Z.W. with five wheels per side. Initially, the Z.W. was designed for the 10 ton weight category. Later, the limit was raised to 12 tons, and the final mass of the Z.W., now indexed PzIII Ausf. A, was 15 tons. The coil spring suspension, sensitive to increase in weight, behaved poorly in these conditions.
First of all, this introduced oscillations, best observed when the tank made a sudden stop. Even the introduction of shock absorbers on the mass produced PzIII Ausf. A didn't help.
PzIII Ausf. B on maneuvers. The round brake access hatches, characteristic of this variant, are visible.
In order to play it safe. the 6th Armament Directorate ordered two extra chassis from Daimler-Benz towards the end of 1935. The first of these was indexed Z.W.3. It had improved cooling system fans, a five-speed gearbox, reinforced brakes, and reinforced turning mechanisms. The idler diameter was increased to 770 mm and the number of road wheels grew from 5 to 8 per side. They were joined into two groups of two bogeys each and the coil springs were replaced with two large leaf springs. The amount of return rollers increased to three per side.
Another novelty was the introduction of the Maybach HL 108 engine. As for the second tank, the Z.W.4, it retained the old engine, but its suspension changed similar to that of the Z.W.3. However, there was one leaf spring, placed in the center. The front and rear bogeys had one half leaf spring each. The Z.W.4 also used track links widened to 380 mm.
The PzIII Ausf. B used leaf springs instead of coil springs, with 8 road wheels per side.
As a result of trials, the Z.W.3 was put into production. Tanks built on this chassis were called PzIII Ausf. B. The index 2./Z.W. Serie, "Z.W. tanks second series", was also used. 15 tanks with serial numbers 60201-60215 were ordered. Eight tanks were ready by November 9th, 1937, two of which were sent to the 5th Tank Regiment in Wünsdorf, and the rest to a training facility in Putlos. Two more tanks ended up in the 1st Tank Regiment on December 6th, 1937.
The remaining five chassis weren't destined to become PzIII Ausf. B. They were used to make Pz.Sfl.III (s.Pak) vehicles, a precursor to the StuG III. Daimler-Benz was supposed to build five more chassis to replace the ones used to make Pz.Sfl.III (s.Pak), but it never happened. Meanwhile, Krupp completed their contract, producing 15 turrets. Five of them lay idly for over two years.
PzIII Ausf. C. The two main differences from its precursor are visible: a new commander's cupola and a redesigned suspension.
Mass production PzIII Ausf. B tanks were different from the experimental Z.W.3. The drive sprockets, idlers, and track links were taken from the PzIII Ausf. A. The same applies to the hull and turret platform.
However, it's easy to tell the PzIII Ausf. B from other early Z.W. tanks due to the round hinged hatches on the front plate for servicing the brakes. The PzIII Ausf. A and all later variants had square hatches without hinges. Both of these solutions were puzzling. Not only did the hatches weaken the front plate, but it was also difficult to service the brakes through them. Crews had to remove over 10 bolts per hatch, which was hardly a cakewalk, as they were positioned in the dirtiest place onthe tank.
The mass production vehicles used the Maybach 108 TR engine. The top speed didn't change, even though the tank's weight increased to 16 tons. The complicated suspension contributed to the weight.
Loading a PzIII Ausf. C, 1939. The tank was modernized: smoke grenade launchers were added to the rear.
The Z.W.4 chassis was also not built in vain. The 6th Armament Directorate didn't think too long before putting it into production. Its mass produced version is known as the PzIII Ausf. C or 3./Z.W. Serie.
Seeing that the round brake maintenance hatches were a bad idea, Daimler-Benz returned to the initial front plate design. As with the second series, the PzIII Ausf. C had the same idler, drive sprocket, and track links as the PzIII Ausf. A. The tanks received improved driver's observation devices, initially designed for the PzII Ausf. A. The shape of the engine compartment roof and rear mudguards changed slightly. Finally, the turret received a new commander's cupola that Krupp designed for the PzIV Ausf. B. It had a 30 mm thick reinforcement ring, which significantly increased protection. However, with 14.5 mm thick regular armour, this improvement was largely psychological.
According to the signed contract, Daimler-Benz began assembling the 3./Z.W. Serie in the fall of 1937. The tank received serial numbers 60301-60315. As for turrets, the situation with them is more interesting. Krupp received a contract for only 4 turrets, the rest was given to Alkett (Altmärkische Kettenfabrik) in Spandau, a suburb of Berlin. This company was formed in 1937 as a tank assembly subsidiary of Rheinmetall-Borsig AG.
Reworked suspension of the PzIII Ausf. D.
Meanwhile, the situation with the 3./Z.W. Serie order changed. Trials showed that the idea of half leaf springs in the front and rear needs more work. The redesign didn't end there, and the result was a whole new tank, the PzIII Ausf. D. Since it was formally a modified PzIII Ausf. C, it was included in the 3./Z.W. Serie contract. PzIII Ausf. C tanks were listed as 3a./Z.W. Serie, and PzIII Ausf. D tanks were listed as 3b./Z.W. Serie.
The new modification had a longer rear and a new suspension. Instead of half leaf springs, the front and rear bogeys received full leaf springs, as well as shock absorbers. The suspension for the central bogeys also changed. The tank received a new SSG 76 transmission.
PzIII Ausf. D photographed during the Poland campaign.
The orders for 3a./Z.W. Serie and 3b./Z.W. Serie were filled in parallel, and as such, the tanks aren't always differentiated in documents. PzIII Ausf. D tanks received serial numbers in the 60316-60340 range. The production of 3./Z.W. Serie was completed in late November of 1938. However, this was not the end of PzIII Ausf. D production, as Daimler-Benz still had a contract for 4 PzIII Ausf. B tanks to fill, which was eventually changed to 5 PzIII Ausf. D tanks with serial numbers 60221–60225. For a number of reasons, production lagged behind schedule, and these tanks were only completed in October of 1940. They received turrets from the PzIII Ausf. B.
Pressed into Service
Like the PzIII Ausf. A, tanks from the second and third series were mostly sent to training units. Even when it was clear that war with Poland is coming, more than a third (37 out of 98 PzIIIs) were assigned to the 1st Training Tank Regiment.
Meanwhile, problems with the suspension continued to plague the PzIII with shocking regularity. The replacement of the coil springs didn't help, since that just caused new problems. First of all, the small road wheels had a short lifespan. The problem could be solved by increasing their diameter, but that would require changing the suspension design. The complexity of the suspension was not reduced compared to the PzIII Ausf. A, far from it. In addition, tanks from the 1st and 2nd series had problems with brakes, which could only be solved by a redesign.
The oiling diagram for the PzIII Ausf. D shows how much of the tank's internal space the leaf spring suspension ate up.
The tanks were gradually modernized during service. First of all, smoke grenade launchers were installed in the rear starting on August of 1938. Several tanks received front and rear Notek lights. Two 5 meter tow cables were introduced to replace the stock 10 meter one that tore often.
Despite various modifications, the Germans understood that the characteristics of the tanks will not radically improve. The first three series of Z.W. tanks were obsolete as soon as they entered production, first of all due to their armour. Fighting in Spain showed that a tank needs to have at least 30 mm of armour to protect it from 20 mm autocannons. 14.5 mm of armour protected the tank only from rifle bullets.
Early PzIII tanks knocked out during the Polish campaign. Polish 37 mm armour piercing shells passed through their armour like it wasn't there.
Despite such disappointing conclusions regarding the combat qualities of the PzIII, they weren't spared from participating in combat. The reason was simple: there weren't enough tanks. As of September 1st, 1939, the Wehrmacht's combat units had only 51 PzIII tanks. The backbone of the Panzerwaffe was composed of PzI and PzII tanks, and the most numerous German medium tank was the PzIV, a tank initially intended as a support vehicle.
In this situation, the idea of making the B.W. (PzIV) on the Z.W. chassis that was around between the summers of 1937 and 1938 was preposterous. Daimler-Benz was incapable of making a proper tank over the span of several years, and its dreams of receiving a contract for a support tank were an impossible fantasy.
The comedy of this story is increased by the fact that the PzIII eventually became the support tank, and the PzIV once again became the most common medium tank in the Wehrmacht. History has interesting plot twists.
As of September 1st, 1939, the 1st Tank Regiment of the 1st Tank Division had the most PzIIIs (20) out of any unit. The other regiments only had 3 tanks of this type. The result of their use in battle was disappointing. Almost half of the tanks used in the campaign (24) were lost. Tanks were lost both to enemy fire as well as technical breakdowns. Knocked out or broken tanks were often used as parts donors. Large scale use of 37 mm cannons and anti-tank rifles gave these tanks low odds of survival. Polish 7TP tanks and TK-S tankettes armed with 20 mm cannons were worthy enemies of the PzIII.
Most PzIII Ausf. A-D tanks that were reclaimed in the winter of 1940 were sent to training units. Some of them had their turrets and turret platforms removed.
These results were properly understood by the Germans. A program was launched in February of 1940 to replace all PzIII Ausf. A-D tanks with more modern modifications. By the end of the month, 34 early tanks were reclaimed and sent to be repaired. They did not return to the front lines and spent the rest of their lives in training units. Some tanks had their turret platforms removed, which made them easier to drive and allowed them to carry more students.
Broken down and abandoned PzIII Ausf. D with an Ausf. B turret from Panzer-Abteilung z.b.V.40, fall-winter 1941. Looks like passing units took the tank apart for parts.
The story of the PzIII Ausf. B-D could end here, if not for a few "early" tanks that reached the front lines in 1941. These were the PzIII Ausf. D with Ausf. B turrets that were stuck in production since 1937. Panzer-Abteilung z.b.V.40 (40th Tank Battalion for Special Operations) was formed in March of 1940. The battalion's first mission was during the occupation of Norway, where the experimental Nb.Fz. tanks fought. The obsolete early PzIIIs were "banished" here.
On June 22nd, 1941, the battalion was a part of the 36th Army Corps. It fought in the polar regions, but did not show itself well. An attempt to attack Murmansk ended with nothing. The unreliable suspension of the PzIII Ausf. D led to a gradual loss of these tanks over time for technical reasons.
Commander's Long Liver
The fate of other vehicles in the leaf spring PzIII family was different. Their story begins in late October of 1935. The 6th Armament Directorate proposed a commander's vehicle on the Z.W. chassis that would be used to coordinate the actions of regular tanks. This vehicle would carry a powerful radio.
Daimler-Benz took the task of designing the Befehls-Panzerkampfwagen. In October of 1936, its name was changed to Pz.Bef.Wg. (Panzerbefehlswagen), and the indices Sd.Kfz.266, Sd.Kfz.267 and Sd.Kfz.268 were attached to the project. The design work used the PzIII Ausf. D as its foundation and arrived at a discouraging conclusion. Even though the size of the PzIII's fighting compartment was much greater than that of the PzI, the chassis of the current commander's tank, it became clear by 1938 that there was no room to retain the stock armament.
The 37 mm gun and one of the coaxial machineguns were removed. Dummies were installed instead to keep the tank looking like a regular one. The armament was reduced to one machinegun in the turret, which was installed in a ball mount. The tank also lost its rotating turret, since a large frame antenna was added behind it.
Pz.Bef.Wg. Ausf.D1. This tank is noticeably different from the PzIII Ausf. D.
This was not the end of the metamorphosis of the PzIII on its way to becoming a commander's tank. The vehicle, named Pz.Bef.Wg. Ausf.D1, changed noticeably. It received a converted PzIII Ausf. E turret. Aside from dummy armament, it received a hatch for a telescoping antenna in the roof, and a port for the antenna wire was added to the rear of the hull. The shape of the hull itself was changed. The observation ports and hull machinegun were also borrowed from the PzIII Ausf. E, and the brake maintenance hatches that weakened the front plate were removed. The engine compartment roof was also redesigned.
The thickness of the armour of the commander's tank was increased to match the PzIII Ausf. E, so that 20 mm cannons wouldn't be a dangerous enemy. The tank received a second whip antenna.
The suspension was also changed. The drive sprockets from the PzIII Ausf. E were used, as well as new idlers. The suspension was changed slightly. This was necessary since the mass of the tank grew to 18.2 tons. The maximum speed dropped to 39 kph.
The large antenna above the engine deck is the only indication that this is a commander's tank.
Initially, production of the 3c./Z.W. Serie (the name of the Pz.Bef.Wg. Ausf.D1 in some documents) was supposed to start in the fall of 1938. Experimental prototypes were supposed to appear even earlier, but production fell behind schedule for various reasons. The first vehicle of the series with its serial number in the 60341-60370 range was finished by April of 1938. 26 tanks were completed by the end of December of 1938, and the remaining four were finished by March of 1939. 24 of the tanks were of the Sd.Kfz.267 modification, and 6 Sd.Kfz.268. The Wehrmacht had 32 commander's tanks (including the later Pz.Bef.Wg. Ausf.E) at the start of the Polish campaign. 13 of them were lost.
Soviet tankers in front of a Pz.Bef.Wg. Ausf.D1. Judging by the shoulderboards, the photo was taken no earlier than 1943.
Even though about a third of the tanks was lost at the start of WWII, their service turned out to be long. Of course, the suspension had its problems, but the Pz.Bef.Wg. Ausf.D1. wasn't bad as a commander's tank. The key component was the radio, not the suspension, and it usually kept back to the second line. Thanks to this, these tanks survived the French campaign of spring-summer of 1940 and actively participated in the fighting on the Eastern Front. Some tanks survived until 1942, at least. The author's collection includes a photograph of a tank that was abandoned and captured by the Red Army no earlier than 1943.