In 1935 contracts were issued by the Germany Army Weapons Department for prototypes of two main battle tanks.5,7,9 One would have a high velocity gun for battling tanks and the other carrying a large caliber gun to support it by firing HE ammunition. Guderian intended for this model to be the primary tank of the Panzer divisions. The medium tank was to be 15,000 kg, but this was later modified to 24,000 kg, which was the limit for the Heer's (Army) bridging equipment.2
The Mechanized Troops Inspectorate wanted a 50 mm main gun but Waffenamt (Ordnance Department) felt that the standard 37 mm infantry gun was sufficient and would ease supply as it was also the standard size of the infantries anti-tank weapon.1,2,4,6,8,9 A large turret ring was kept so that the tank could later have a larger gun installed.2,4,5,9 By 1938 the Ordnance Department decided to ask Krupp to develop a turret to install the 50 mm into.1,2
To conceal the development of the vehicle it was called the Zugführerwage (ZW, platoon commander's vehicle).2,6,7,8
On September 27, 1939, PzKpfw III was accepted as a standard issue after its success in Poland.2
The hull was divided into 4 prefabricated welded assemblies: hull, front & rear superstructure, and turret.2,9 The hull had three sub-assemblies: main hull, front superstructure carrying the turret, rear superstructure with the engine.1 These sections were welded, and then all the sections were bolted together.1 A bulkhead divided the hull section, with the front having the gearbox and steering.1
The turret, which was welded, didn't have a rotating platform, instead it had seats suspended from the turret.1,2 There were large hinged doors, that had pistol ports and vision slits, on the turret sides.1,2
The commander had cupola that allowed all round view and could communicate via throat microphone.2 He had a central raised seat between the gunner and loader.2 The driver, radio operator, and commander were connected to the external radio.2
The driver of the PzKpfw III sat on the left in the front of the hull and the radio operator / machine gunner sat to the right.1,2,9 In the front superstructure the driver looked out through a vision block.2 Through visor blocks that were behind armored flaps the driver and machine gunner could look out through the sides.2
Escape doors were mounted centrally on both sides of the hull, which was later eliminated in the last two models.1,2 The main hull also had doors that gave access to the brake mechanism and allowed for escape of the crew.1,2
Daimler-Benz AG of Berlin-Marienfelde, Krupp AG of Essen, MAN of Nürnberg, and Rheinmetall-Borsig of Berlin created prototypes to the specifications given by the Waffenamt.2,5,6,7,9 Krupp designed a vehicle with a leaf spring and bogie wheel suspension based on it's experience with locomotive production.1,2 Daimler-Benz favored torsion bar springs due to it's experience with automobiles.1,2,8
In 1936 the first prototypes appeared and were tested at Kummersdorf and Ulm.2,7 Daimler-Benz's model was selected by the Heereswaffenamt for production.2,7,8,9,10 In September 1939 it was adopted for mass production.10
Ten pre-production, 1/ZW, vehicles were completed in 1936.7
On July 17, 1941, a Wehrmacht tank committee wanted the construction of 7,992 PzKpfw IIIs to equip 36 panzer divisions in the future.2
Altmärkische Kettenfabrik GmbH (ALKETT)2
Daimler-Benz AG (Berlin-Marienfelde)2
Fahrzeug-und Motorenbau GmbH (FAMO, Breslau)2
Henschel & Sohn AG (Mittelfeld-Kassel, No. 111 plant)2
Maschinenfabrik Augsburg-Nürnberg AG (Nürnberg)2
Mühlenbau-und Industrie AG (MIAG) (Amme Braunschweig)2
PzKpfw III Ausf E: The suspension problems were fixed in the PzKpfw III Ausf E with its torsion bar suspension.6 The engine output was increased.6 The mantlet was moved to the outside of the turret.6 Later production models had a 5 cm gun.6
Panzerkampfwagen III Ausf N als Schienen-Ketten Fahrzeug SK1: 2 or 3 prototypes were produced during late 1942 and early 1943. The suspension was altered to allow railway bogie wheels to be mounted on the belly to allow travel on railroad tracks. These wheels could be retracted. Modified to allow for railway wheels to be used on rail lines.3 Prototypes could go 100 kph.3 The wheels could be retracted into hull to allow for normal cross country movement.3
Panzerbefehlswagen III (SdKfz 266, SdKfz 267, and SdKfz 268)6,8: Command conversions.6,11 Additional radios and aerials.6
Panzerbeobachtungswagen III (SdKfz 143)6,8: Manufactured in 1941 to be a artillery observation tank.6,11 The gun in the turret was a dummy barrel offset to allow for a machine gun to fire through the mantlet.6 Additional radios and observation equipment was installed.6
Panzerkampfwagen III Famo Suspension: Prototype produced in 1942 with interleaved road wheels.4
Panzerkampfwagen III mit Schachtellaufwerk: Prototype to use large interleaved roadwheels.3
Pionierpanzerwagen auf Fahrgestell Panzerkampfwagen III: PzKpfw III Ausf L and PzKpfw III Ausf M had turrets removed and a wooden cargo area was made. On each side of the chassis a Pionierbruecken (bridge) piece was placed.
Schlepper III6: Turrets replaced by a wooden platform.6 Used for transporting supplies.6
Tauchpanzer III, PzKpfw III (Tauchfähig)6,11: "Diving tank." 168 PzKpfw III Ausf F, PzKpfw III Ausf G, PzKpfw III Ausf H, and PzBefWg III Ausf Es were converted from June to October 1940 for Operation Seeloewe (Sealion, invasion of Britain) by the 18th Panzer Regiment of the 18th Panzer Division. The air intakes were closed by rubber seals and the exhausts had non-return valves installed.2 An inflatable rubber seal was placed around turret ring.2 The hull machine gun and commander's cupola had rubber covers installed.2 There was a pump that removed excess water that got inside tank. When under water it would get air from a 59'7/18 m7 long and 8" diameter hose which was attached to a float that on later models had a radio antenna.2 It could operate to a depth of 49'7/15 m7 for around 20 minutes. Explosive charges were installed to the seals to be set off to remove the seals when tank reached dry land.2 A command vessel would communicate to the submerged tank via the radio to guide it.
In August 1940 the first prototypes were tested. A landing test was done in late 1940 with a crane ship called "Viper" and the small freighter "Hans Herbert". They were fitted with ramps to allow the tanks into the water.
Four sections of volunteers from existing regiments were trained on the Island of Sylt.
After the cancellation of Seeloewe the Tauchpanzers were moved to training areas in early 1941. Tanks were modified by having an 11' long and 3" diameter steel snorkel installed over the commander's cupola which replaced the flexible tube. In April 1941 all Tauchpanzers of Panzer Regiment 18 were sent to Eberswalde and diving exercises were carried out at Werbelliner Lake.
Used in crossing River Bug on June 22, 1941 by Panzer Regiment 18.2,7 After this the tanks were used by both the 6th and 18th Panzer Divisions.2
Four Tauchpanzer-Abteilung (A to D) were formed.
349 PzKpfw IIIs were available for the invasion of France.2,7,8
After the campaign in France, Hitler ordered the up gunning to the 50 mm L/60. However, the army continued to fit the 50 mm L/42 version to speed up production. After the invasion of Russia Hitler found out that his orders were not followed and immediately a 50 mm L/60 version was designed (PzKpfw III Ausf J/1). The 50 mm L/60 had a muzzle velocity of 2,700 ft/sec with AP rounds and 3,835 ft/sec with PzGr (Panzergranate) 40 round.
Invasion of Russia
965 PzKpfw IIIs were deployed to fighting units out of a total of 3,332 tanks used in the opening days of Operation Barbarossa.7
On October 4, 1941, at Mtsensk (near Orel), the 4th Panzer Division established a bridgehead over the River Lisiza near Kamenewa when the Soviets attacked.7 Approximately 50 T-34s and KV-1s were waiting in a wood near Woin.7 This attack destroyed 10 PzKpfw IIIs and sent the 4th Panzer Division back across the river.7 All fire from the 50 mm L/42 guns bounced off the KV-1 armor.7
By October 1943, only 5 Panzer Divisions still had PzKpfw IIIs.7 By mid 1944 there were nearly no PzKpfw IIIs in front line units.7 There were still almost 700 in training and garrison units.7
The 12th Panzer Division did have nine on June 27, 1944, at the beginning of the Russian Operation Bagration.7
The Afrika Korps was supplied with PzKpfw III Ausf J/1s in April 1942.7 These were the top tank in the theater.7 They were used in June 1942 at the Gazala battles.7 Soon, with the arrival of the American Sherman's these became outclassed.7