At the time, German (non-light) tanks were expected to carry out one of two primary tasks when assisting infantry in breakthroughs, and exploit gaps in the enemy lines where opposition had been removed, moving through and attacking the enemy's unprotected lines of communication and the rear areas. The first task was direct combat against other tanks and other armoured vehicles, requiring the tank to fire armour piercing (AP) shells. 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 24,000 kg (53,000 lb) and a top speed of 35 km/h (22 mph). It was intended as the main tank of the German Panzer divisions, capable of engaging and destroying opposing tank forces, and was to be paired with the Panzer IV, which was to fulfil the second use: dealing with anti-tank guns and infantry strong points, such as machine-gun nests, firing high-explosive shells at such soft targets. Such supportive tanks designed to operate with friendly infantry against the enemy generally were heavier and carried more armour.
The direct infantry-support role was to be provided by the turret-less Sturmgeschütz assault gun, which mounted a short-barrelled gun on a Panzer III chassis.
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 Ausführung A. (Ausf. A), came off the assembly line in May 1937; 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, usually using eight relatively small-diameter road wheels before the torsion-bar suspension of the Ausf. E was standardized, using the six road wheel design that became standard. The Panzer III, along with the Soviet KV heavy tank, was one of the early tanks to use this suspension design first seen on the Stridsvagn L-60 a few years earlier.
A distinct feature of the Panzer III, influenced by British Vickers tanks (1924), was the three-man turret. This meant that the commander was not distracted with another role in the tank (e.g. as gunner or loader) and could fully concentrate on maintaining awareness of the situation and directing the tank. Most tanks of the time did not have this capability, providing the Panzer III with a combat advantage versus such tanks. For example, the French Somua S-35's turret was manned only by the commander, and the Soviet T-34 originally had a two-man turret crew. The Panzer III, as opposed to the 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 armour and gun power. To meet the growing need to counter these tanks, the Panzer III was up-gunned with a longer, more powerful 50-millimetre (1.97 in) gun and received more armour but still was at disadvantage compared with the Soviet 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-millimetre (2.95 in) KwK 37 L/24 cannon, the same short-barreled howitzer-like gun used for the initial models of the Panzer IV, a low-velocity gun designed for anti-infantry and close-support work. For defensive purposes, the Ausf. N was equipped with rounds of HEAT ammunition that could penetrate 70 to 100 millimetres (2.76 to 3.94 in) of armour depending on the round's variant, but these were strictly used for self-defence.
The Japanese government bought two Panzer IIIs from their German allies during the war (one 50 mm and one 75 mm). Purportedly this was for reverse engineering purposes, since Japan put more emphasis on the development of new military aircraft and naval technology and had been dependent on European influence in designing new tanks. By the time the vehicles were delivered, the Panzer III's technology was obsolete.
The Panzer III Ausf. A through C had 15 mm (0.59 in) of rolled homogeneous armour on all sides with 10 mm (0.39 in) on the top and 5 mm (0.20 in) on the bottom. This was quickly determined to be insufficient, and was upgraded to 30 mm (1.18 in) on the front, sides and rear in the Ausf. D, E, F, and G models, with the H model having a second 30 mm (1.18 in) layer of face-hardened steel applied to the front and rear hull. The Ausf. J model had a solid 50 mm (1.97 in) plate on the front and rear, while the Ausf. J¹, L, and M models had an additional layer of offset 20 mm (0.79 in) homogeneous steel plate on the front hull and turret, with the M model having an additional 5 mm (0.20 in) Schürzen spaced armour on the hull sides, and 8 mm (0.31 in) on the turret sides and rear. This additional frontal armor gave the Panzer III frontal protection from most British and Soviet anti-tank guns at all but close ranges. However, the sides were still vulnerable to many enemy weapons, including anti-tank rifles at close ranges.
The Panzer III was intended to fight other tanks; in the initial design stage a 50-millimetre (1.97 in) gun was specified. However, the infantry at the time were being equipped with the 37-millimetre (1.46 in) 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-millimetre (1.97 in) gun should a future upgrade be required. This single decision later assured 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 gun 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 gun - 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 75 mm gun.
All early models up to and including the Ausf. F had two 7.92-millimetre (0.31 in) MG 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.
The Panzer III Ausf. A through C were powered by a 250 PS (184 kW), 12-cylinder Maybach HL 108 TR engine, giving a top speed of 32 km/h (20 mph) and a range of 150 km (93 mi). All later models were powered by the 300 PS (221 kW), 12-cylinder Maybach HL 120 TRM engine. Regulated top speed varied, depending on the transmission and weight, but was around 40 km/h (25 mph).
The fuel capacity was 310 l (68.2 gal), and while extra fuel could be carried in an auxiliary fuel over the rear, this was not often employed. Range on the main tank was 145 km (90 mi) to 155 km (96 mi) on road, or 95 km (59 mi) crosscountry.
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 armoured forces. Only a few hundred Ausf. A through F were available in these campaigns, most armed with the 37-millimetre (1.46 in) gun. They were the best medium tank available to the Germans and outclassed, in both firepower and armour, most of their opponents, such as the Polish 7TP, French R-35 and H-35 light tanks and the Soviet T-26 light tank and BT cavalry 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-millimetre (1.97 in) KwK 38 L/42 cannon, which also equipped the majority of the tanks in North Africa. Initially, the Panzer IIIs were outclassed 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 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-millimetre (1.97 in) gun 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 metres (1,600 ft). Against the KV tanks, it was a threat if armed with special high velocity tungsten rounds. In addition, to counter anti-tank 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 armoured fighting vehicle design of World War II.
By the end of the war, the Panzer III saw 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.Panzer III Ausf. A - Prototype; only 8 armed and saw service in Poland. Armed with 3.7 cm KwK 36 L/46.5 main gun, 250 PS HL 108 engine.
Panzer III Ausf. B - Prototype; some saw service in Poland.
Panzer III Ausf. C - Prototype; some saw service in Poland.
Panzer III Ausf. D - Prototype; some saw service in Poland and Norway. Armour upgraded to 30 mm front, side and back.
Panzer III Ausf. E - Suspension redesigned, switching from leaf-springs to torsion-bars, now using 6 larger roadwheels per side. 300 PS HL 120 engine.
Panzer III Ausf. F - improved Ausf. E, first mass-production version, late production armed with 5 cm KwK 38 L/42 main gun.
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.
Panzer III Ausf. H - 5 cm KwK 38 L/42 as standard gun. Bolt-on armour added to front and rear hull (30 mm base + 30 mm plates).
Panzer III Ausf. I - Variant mentioned in Allied intelligence reports but not an actual existing vehicle. Possible confusion with Ausf. J.
Panzer III Ausf. J - Hull and turret front armour increased to solid 50 mm plate. Some were produced with 5 cm KwK 39 L/60 gun and later redesignated Ausf. L.
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 - Redesignated Aus. J equipped with long 5 cm gun, 20 mm stand-off armour plates on hull and turret front
Panzer III Ausf. M - Minor modifications of the ausf. L such as deep-wading exhaust and Schürzen side-armour panels.
Panzer III Ausf. N - Infantry support tank, armed with a short-barrelled 7.5 cm KwK 37 L/24 gun.
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 5 cm 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-millimetre (2.95 in) 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-millimetre (3.00 in) S-1 gun (cheaper version of the F-34) in a limited-traverse mount. The armour was 35 millimetres (1.38 in) thick on the casemate front, 50 millimetres (1.97 in) in the hull front, and 30 millimetres (1.18 in) 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 to 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.
M3 Lee : American equivalent
T-34 : Soviet equivalent medium tank
T-50 : Soviet equivalent light tank
Type 97 Chi-Ha : Japanese equivalent
38(t) : Czech equivalent