Panzer III

Panzer III was the common name of a medium tank that was developed in the 1930s by Germany and was used extensively in World War II. The official German designation was Panzerkampfwagen III Sd Kfz. 141 (abbreviated PzKpfw III) translating as "armoured fighting vehicle". It was intended to fight other armoured fighting vehicles and serve alongside the infantry-supporting Panzer IV; however, as the Germans faced the formidable T-34, stronger anti-tank guns were needed. Since the Panzer IV had a bigger turret ring, the role was reversed. The Panzer IV mounted the long barreled 7.5 cm KwK 40 gun and engaged in tank-to-tank battles. The Panzer III became obsolete in this role and for most purposes was supplanted by the Panzer IV. From 1942, the last version of Panzer III mounted the 7.5 cm KwK 37 L/24, better suited for infantry support. Production of the Panzer III ended in 1943. However, the Panzer III's capable chassis provided hulls for the Sturmgeschütz III until the end of the war.

Development history
On January 11, 1934, following specifications laid down by Heinz Guderian, the Army Weapons Department drew up plans for a medium tank with a maximum weight of 24000 kg and a top speed of 35 km/h. It was intended as the main tank of the German Panzer divisions, capable of engaging and destroying opposing tank forces.

Daimler-Benz, Krupp, MAN, and Rheinmetall all produced prototypes. Testing of these took place in 1936 and 1937, leading to the Daimler-Benz design being chosen for production. The first model of the Panzer III, the Ausf. A, came off the assembly line in May 1937, and a total of ten, two of which were unarmed, were produced in that year. Mass production of the Ausf. F version began in 1939.

Between 1937 and 1940, attempts were made to standardize parts between Krupp's Panzer IV and Daimler-Benz's Panzer III.

Much of the early development work on the Panzer III was a quest for a suitable suspension. Several varieties of leaf-spring suspensions were tried on Ausf. A through Ausf. D before the torsion-bar suspension of the Ausf. E was standardized. The Panzer III, along with the Soviet KV heavy tank, was one of the first tanks to use this suspension design.

A distinct feature of Panzer III, influenced by British Vickers tanks, was the three-man turret. This meant that commander was not distracted with either loader's or gunner's tasks and could fully concentrate on maintaining situational awareness. Most tanks of the time did not have this capability, providing the Panzer III with a potential combat advantage. For example the French Somua S-35, had only one-man turret crew, and the Soviet T-34 (originally) had two-men. The practical importance of this feature is signified by the fact that not only all the further German tank designs inherited it, but also later into the war, most of the Allied tanks' designs either quickly switched to the three-man turret, or were abandoned as obsolete.

The Panzer III, as opposed to Panzer IV, had no turret basket, merely a foot rest platform for the gunner.

The Panzer III was intended as the primary battle tank of the German forces. However, when it initially met the KV-1 and T-34 tanks it proved to be inferior in both armor and gun power. To meet the growing need to counter these tanks, the Panzer III was up-gunned with a longer, more powerful 50 mm cannon and received more armour although this failed to effectively address the problem caused by the KV tank designs. As a result, production of self-propelled guns, as well as the up-gunning of the Panzer IV was initiated.

In 1942, the final version of the Panzer III, the Ausf. N, was created with a 75 mm KwK 37 L/24 cannon, a low-velocity gun designed for anti-infantry and close-support work. For defensive purposes, the Ausf. N was equipped with rounds of hollow charge ammunition which could penetrate 70 to 100 mm of armour depending on the round's variant but these were strictly used for self-defense.

The Japanese government allegedly bought two Panzer III's from their German allies during the war. Purportedly this was for reverse engineering purposes, since Japan put more emphasis on the development of new military aircraft and naval technology and relatively little on the development of new tanks. The vehicles apparently weren't delivered until 1943 however, by which time much of the Panzer III's technology had arguably already become obsolete.

Armour
The Panzer III Ausf. A through C had 15 mm of homogeneous steel armor on all sides with 10 mm on the top and 5 mm on the bottom. This was quickly determined to be insufficient, and was upgraded to 30 mm on the front, sides and rear in the Ausf. D, E, F, and G models, with the H model having a second 30 mm layer of face-hardened steel applied to the front and rear hull. The Ausf. J model had a solid 50 mm plate on the front and rear, while the Ausf. J¹, L, and the M models had an additional layer of 20 mm of armor on the front hull and turret. This additional frontal armor gave the Panzer III frontal protection from most British and Soviet anti-tank guns at all but close ranges. The sides were still vulnerable to many enemy weapons including anti-tank rifles at close ranges.

Armament
The Panzer III was intended to fight other tanks; in the initial design stage a 50 mm cannon was specified. However, the infantry at the time were being equipped with the 37 mm PaK 36, and it was thought that in the interest of standardization the tanks should carry the same armament. As a compromise, the turret ring was made large enough to accommodate a 50 mm cannon should a future upgrade be required. This single decision would later assure the Panzer III a prolonged life in the German Army.

The Ausf. A to early Ausf. F were equipped with a 3.7 cm KwK 36 L/45 which proved adequate during the campaigns of 1939 and 1940 but the later Ausf. F to Ausf. J were upgraded with the 5 cm KwK 38 L/42 and the Ausf. J¹ to M with the longer 5 cm KwK 39 L/60 cannon in response to increasingly better armed and armoured opponents.

By 1942, the Panzer IV was becoming Germany's main medium tank because of its better upgrade potential. The Panzer III remained in production as a close support vehicle. The Ausf. N model mounted a low-velocity 7.5 cm KwK 37 L/24 cannon - the same used by the early Panzer IV Ausf. A to Ausf. F models. These guns had originally been fitted to older Panzer IV Ausf A to F1 models and had been placed into storage when those tanks had also been up armed to longer versions of the 75mm gun.

All early models up to and including the Ausf. F had two 7.92 mm Maschinengewehr 34 machine guns mounted coaxially with the main gun, and a similar weapon in a hull mount. Models from the Ausf. G and later had a single coaxial MG34 and the hull MG34.

Mobility
The Panzer III Ausf. A through C were powered by a 250 PS, 12-cylinder Maybach HL 108 TR engine, giving a top speed of 32 km/h and a range of 150 km. All later models were powered by the 300 PS, 12-cylinder Maybach HL 120 TRM engine. Top speed varied, depending on the transmission and weight, but was around 40 km/h. The range was generally around 155 km.

Combat use
The Panzer III was used in the campaigns against Poland, France, the Soviet Union and in North Africa. A handful were still in use in Normandy, Anzio, Norway, Finland and in Operation Market Garden in 1944.



In the Polish and French campaigns, the Panzer III formed a small part of the German armored forces. Only a few hundred Ausf. A through F were available in these campaigns, most armed with the 37 mm gun. They were the best medium tank available to the Germans and outclassed most of their opponents such as the Polish 7TP, French R-35 and H-35 light tanks.

Around the time of Operation Barbarossa, the Panzer III was numerically the most important German tank. At this time the majority of the available tanks (including re-armed Ausf. E and F, plus new Ausf. G and H models) had the 50 mm KwK 38 L/42 cannon which also equipped the majority of the tanks in North Africa. Initially, the Panzer IIIs were outclassed and outnumbered by Soviet T-34 and KV tanks. However, the most numerous Soviet tanks were the T-26 and BT tanks. This, along with superior German tactical skill, crew training, and the good ergonomics of the Panzer III all contributed to a rough 6:1 favourable kill ratio for German tanks of all types in 1941.



With the appearance of the T-34 and KV tanks, rearming the Panzer III with a longer, more powerful 50 mm cannon was prioritised. The T-34 was generally invulnerable in frontal engagements with the Panzer III until the 50 mm KwK 39 L/60 gun was introduced on the Panzer III Ausf. J¹ in the spring of 1942 (the gun was based on infantry's 50 mm Pak 38 L/60). This could penetrate the T-34 frontally at ranges under 500 m. Against the KV tanks it was a threat if armed with special high velocity tungsten rounds. In addition, to counter antitank rifles, in 1943 the Ausf. L version began the use of spaced armour skirts (schürzen) around the turret and on the hull sides. However, due to the introduction of the upgunned and uparmoured Panzer IV, the Panzer III was, after the Battle of Kursk, relegated to secondary roles, such as training, and it was replaced as the main German medium tank by the Panzer IV and the Panther.

The Panzer III chassis was the basis for the turretless Sturmgeschütz III assault gun, one of the most successful self-propelled guns of the war, and the single most-produced German armored fighting vehicle design of World War II.

By the end of the war, the Pz.III had almost no frontline use and many vehicles had been returned to the factories for conversion into StuG assault guns, which were in high demand due to the defensive warfare style adopted by the German Army by then.

Variants

 * Panzer III Ausf. A - Prototype; 10 produced in 1937, only 8 armed and saw service in Poland.
 * Panzer III Ausf. B, C - Prototype; 15 of each produced in 1937, some of each saw service in Poland.
 * Panzer III Ausf. D - Prototype; 55 produced in 1938, only 30 armed and saw service in Poland and Norway.
 * Panzer III Ausf. E, F - Production models 1939-1940. Armed with 3.7 cm KwK 36 L/46.5 (later 5 cm KwK 38 L/42) guns. 531 produced.
 * Panzer III Ausf. G - More armour on gun mantlet. Armed with 3.7 cm KwK 36 L/46.5 (later 5 cm KwK 38 L/42) gun. 600 produced in 1940-1941.
 * Panzer III Ausf. H - Minor modifications. Bolt-on armor added to front and rear hull (30 mm + 30 mm plates). 308 produced in 1940-1941.
 * Panzer III Ausf. I - Variant mentioned in Allied intelligence reports but not an actual existing vehicle.
 * Panzer III Ausf. J - The hull was lengthened. Front armor increased to 50 mm plate. 482 produced in 1941.
 * Panzer III Ausf. J¹ - Equipped with the longer and more powerful 5 cm KwK 39 L/60 gun. 1,067 produced in late 1941 to mid 1942.
 * Panzer III Ausf. K - Panzerbefehlswagen command tank variant with a modified turret. Carried actual main armament rather than a dummy gun as found on other Panzer III command versions.
 * Panzer III Ausf. L - Uparmored to 50 mm + 20 mm plates. 653 produced in 1942.
 * Panzer III Ausf. M - Minor modifications such as deep-wading exhaust and schurzen. 250 produced in 1942-1943.
 * Panzer III Ausf. N - Armed with a short barreled 7.5 cm KwK 37 L/24 gun, due to 7.5 cm gun's ability to fire HEAT rounds. 700 re-equipped J/L/M models in 1942-1943.

Designs based on chassis

 * Panzerbeobachtungswagen III - Forward artillery observer tank. 262 converted from older Panzer III Ausf. E to H.
 * Bergepanzer III - In 1944, 176 Panzer IIIs were converted to armoured recovery vehicles. Mostly issued to formations with Tiger I tanks.
 * Flammpanzer III Ausf. M / Panzer III (Fl) - Flamethrower tank. 100 built on new Ausf. M chassis.
 * Minenräumer III - Mineclearing vehicle based on a Panzer III chassis with a very highly raised suspension. (Prototype only.)
 * Panzerbefehlswagen III - Command tank with long-range radios. Ausf. D, E and H: dummy main gun; Ausf. J and K: armed with 5cm gun.
 * Sturm-Infanteriegeschütz 33B - A close-support assault gun. Armed with a 15 cm sIG 33, 24 built. 12 used and lost in Stalingrad.
 * Sturmgeschütz III - Assault gun/tank destroyer armed with a 75 mm StuK.
 * The Soviet SU-76i self-propelled gun was based on the chassis of captured German Panzer III and StuG III. About 201 of these vehicles, many captured in the battle of Stalingrad, were converted at Factory No. 37 in 1943 for Red Army service by removing the turret, constructing a fixed casemate, and installing a 76.2 mm S-1 gun (cheaper version of the F-34) in a limited-traverse mount. The armour was 35 mm thick on the casemate front, 50 mm in the hull front, and 30 mm on the hull side. It was issued to tank and self-propelled gun units starting in autumn 1943, and withdrawn to training use in early 1944. Two SU-76i survive: one on a monument in the Ukrainian town of Sarny and a second on display in a museum on Poklonnaya Hill in Moscow. It should not be confused with the Soviet SU-76 series.
 * Tauchpanzer III - Some tanks were converted to amphibious tanks for Operation Sea Lion. Unusually, they were designed to be able to stay underwater rather than float. The idea was that they would be launched near to the invasion shore and then drive to dry land on the sea bottom. The tank was waterproofed, the exhaust was fitted with a one-way valve and air intake was through a hose.