Development of Hitler's Panzers was key to his early overwhelming victories in the East and West. The Panzer I light tank became Germany's first tank development after World War 1 and, though it was limited as a "true" tank in combat, set the foundation for things to come. The Panzer II light tank was developed as a stopgap measurement to help tie the existence of the Panzer Is to the upcoming Panzer III and Panzer IV. The Panzer III was designed to be capable of tangling with any known enemy tank head-on while the Panzer IV was initially developed as an infantry support vehicle. While dominating the field of play for some time, the Panzer III (like the Panzer I and II before it) suffered from being inadequately armed and armored and was eventually replaced by more modern and potent systems in the German arsenal - namely the improved forms of the Panzer IV, the Panther series and the Tiger series. The Panzer III saw service in the Polish, Czech, French and Low Countries campaigns as well as along the Eastern Front in Russia. After its inherent battlefield usefulness was past, the Panzer III chassis served in a handful of conversions, most notably, the StuG III assault gun. Note: To help the reader along, it is important to note the German designation convention for its military vehicles. The abbreviation Pz.Kpf.W. covers "Panzerkampfwagen" and translates to "armored fighting vehicle". Likewise, the abbreviation Sd.Kfz. covers "Sonderkraftfahrzeug" and translates to "special motor vehicle". Ausf is the general term used to cover "model" or "mark" in showcasing a variant of note. Taking all this into account, the Panzer III can also be known by the designation of Pz.KpfW. III as well as Sd.Kfz. 141 while any model variants are covered in the convention of Ausf. A, Ausf. B, Ausf. C and so on. "Ausf." is the abbreviated form of the word "Ausfuhrung meaning simply "model" or "design". Background In early 1934, the German Army Ordnance Department came to the agreement on the future of their armored corps. It was envisioned that the army would be made up of three companies composed of a light-class of medium tanks backed up by a fourth company composed of a dedicated class of medium tanks with better armor and firepower. The idea then was to develop two such medium tanks tasked with two distinct battlefield roles but were still complementary to the entire German process of waging a mobile land battle. The two tanks became the Pz.Kpf.W. III (Sd.Kfz. 141) and the heavier Pz.Kpf.W. IV medium tanks respectively. The Panzer III would be called to take on the role of tank killer - that is, square off against enemy armor at range - while the Panzer IV would be mainly an infantry support tank. German General Heinz Guderian laid down the specifications for the desired light-medium tank. 1935 saw prototype development contracts issued by the Weapons Department to Daimler-Benz, Krupp, MAN and Rheinmetall-Borsig. The new "light" medium tank would be armed with a more potent 37mm high-velocity main gun armament than her predecessors and supplemented by machine guns - two in the turret as co-axial mounts and a third in a flexible bow mount. The selection of the 37mm armament was a logistical one at this point for German infantry were already using the 37mm anti-tank gun (as the 3.7-cm PaK) in some number by this point. However, the decision to go with the 37mm main gun armament ran into some opposition from senior German officers (including Guderian) who believed that the new tank should be armed with a 50mm/5-cm main gun. As such, the compromise became the fitting of the 37mm gun for the time being, with a special turret ring made to accept a 50mm main gun in the future. The prototype vehicles were evaluated in 1936 with a 15-ton Daimler-Benz submission declared the winner. The First Gun The initial Panzer III armament centered around the high-velocity 3.7-cm Kw.K. L/45 main gun. The weapon was capable of firing armor-piercing (AP) and high-explosive (HE) rounds and proved most effective at close ranges where armor thickness of up to 70mm could be pierced. This value, however, dropped off dramatically at increased ranges. Projectile torque was accomplished through the internal rifling of the gun barrel - a standard practice of all German World War 2 tanks. The Panzer III Ausf. A, Ausf. B, Ausf. C and Ausf. D Daimler-Benz advanced its design and produced the Pz.Kpf.W. III Ausf. A. Power was supplied by a Maybach liquid-cooled gasoline engine of 250 horsepower output. The system featured five large-diameter road wheels to each track side with coil spring suspension. This suspension system was deemed inadequate by the German Army and, as such, further developmental models soon appeared in the Ausf. B, Ausf. C and Ausf. D, each fitting various suspension solutions (Ausf. D also fitted a revised cupola and thicker armor). These three further developments brought about use of eight small road wheels with leaf spring suspension. The hunt for the perfect suspension delayed all full-scale production of the Panzer III. Nevertheless, the German invasion of Poland began on Hitler's schedule, this being September 1st, 1939, with whatever Panzer Is, IIs and limited-quantity IIIs were on hand. A total of 75 Pz.Kpf.W. Ausf. A, Ausf B., Ausf. C and Ausf. D tanks were produced in whole. Combat actions in Poland quickly showed the Panzer III Ausf. B, Ausf. C and Ausf. D to be insufficiently armored for the task at hand. Polish anti-tank guns could penetrate the 15mm-thick steel armor of these early Panzers with relative ease. Coupled with the suspension troubles, these Panzer IIIs faced early retirement and were eventually withdrawn from service before the Invasion of France in May of 1940. By that time, some 349 new Panzer IIIs would be made available to the Wehrmacht. The Panzer III Ausf. E The Pz.Kpf.W. III Ausf. E was developed around a new torsion bar suspension system for its new six road wheel layout (doubled on each track side for an actual total of 24 road wheels). After-action evaluation from engagements during the Polish campaign brought about an increase in armor protection to 30mm thickness along all major structural facings. While this worked well to increase crew and system protection, the added cost in weight increased to 21 tons. The increase led to the selection of a newer and more powerful Maybach powerplant now outputting 300 horsepower. The gun of choice was the 3.7-cm Kw.K. 36 L/46.5 series main gun (though later retrofitted with the 5-cm Kw.K. 38 L/42 series). The German Army Ordnance Office liked what it had and officially cleared the Pz.Kpf.W. Ausf. E for mass production. Ninety-six such vehicles were produced from 1938 through 1939. The Panzer III Ausf. F The Pz.Kpf.W. III Ausf. F was a slightly modified - though similar - version of the Ausf. E with six road wheels to a track side. Ausf. F featured the implementation of cast steel brake ventilation ducts and repositioned final drives along the front hull plate. The main gun was the 3.7cm Kw.K. 36 L/46.5 and (later) the 5-cm Kw.K. 38 L/42 series. The Pz.Kpf.W. III Ausf. F was produced in 435 examples from late 1939 through the mid-way point of 1940. Upon their inception into service, both the Ausf. E and the Ausf. F were the Panzer IIIs of choice for the Invasion of France. The 5-cm Kw.K. L/42 (50mm) Main Gun The original 37mm main gun armament proved inferior from the start, much to the chagrin on the part of senior German Army officials convinced of the type's inadequate power on the modern battlefield as it was. As such, the move to a more powerful 50mm gun was finally enacted with the selection and installation of the 5-cm Kw.K. 39 L/42. The 50mm gun was immediately a more capable component and could fire a broader range of projectiles over the 37mm system it replaced. Despite its upgrade over the original 37mm guns, this 50mm system wasn't Hitler's first choice as the main armament for the new-model Pz.Kpf.W. IIIs (Hitler played a greater role in weapons development as the war progressed, often times to the detriment of the projects). In February of 1941, he explicitly stated that the Pz.Kpf.W. III be armed with the 5-cm Kw.K. 39 L/60, a gun barrel of higher velocity and longer length. The major problem with this requirement was that the Kw.K. 39 L/60 was in the short supply. Additionally, the Ordnance Department believed that their selection of the shorter-barrel 50mm was the right (and better) choice. However, after the opening rounds that was the invasion of the Soviet Union (through Operation Barbarossa), Hitler was actually proven correct. 1,440 Panzer IIIs were fielded in the offensive and the 50mm-armed systems - though excellent against the light fast tanks of the Red Army -proved ineffective against the thickly-armored Soviet T-34 and KV-1 tanks, with reports of 50mm projectiles seemingly bouncing off Soviet turrets and hulls. Shortly thereafter, the longer higher-velocity 50mm gun barrel - the one originally endorsed by Hitler - became standard through the middle of production for the Pz.Kpf.W. III Ausf. J models. All other earlier Pz.Kpf.W. IIIs in circulation also had their main guns retrofitted as such. Conversions to the more lethal gun took place from the end of 1941 through 1943, producing some 2,000 more-capable Pz.Kpf.W. IIIs. By 1942, the old original 37mm main guns were all but non-existent across the war's ever-expanding fronts. The Panzer III Ausf. G The Ausf. G emerged from the Ausf. E and Ausf. F developments. Pz.Kpf.W. III Ausf. G fitted an all-new commander's cupola and a revised driver's vision block. Steel plates of 30mm thickness were added to the existing 30mm structure for vastly improved frontal armor protection and a more powerful engine was introduced to compensate for the added weight. The new steel plate additions proved so effective that they were retrofitted onto preceding Ausf. E and Ausf. F models. The main gun was the 5-cm Kw.K. 38 L/42 series while the second 7.92mm co-axial machine gun was dropped from the turret design. The Ausf. G was produced in 600 examples from early 1940 into 1941. The Ausf. G fought in limited quantity in the invasion of France.

Development of Hitler's Panzers was key to his early overwhelming victories in the East and West. The Panzer I light tank became Germany's first tank development after World War 1 and, though it was limited as a "true" tank in combat, set the foundation for things to come. The Panzer II light tank was developed as a stopgap measurement to help tie the existence of the Panzer Is to the upcoming Panzer III and Panzer IV. The Panzer III was designed to be capable of tangling with any known enemy tank head-on while the Panzer IV was initially developed as an infantry support vehicle. While dominating the field of play for some time, the Panzer III (like the Panzer I and II before it) suffered from being inadequately armed and armored and was eventually replaced by more modern and potent systems in the German arsenal - namely the improved forms of the Panzer IV, the Panther series and the Tiger series. The Panzer III saw service in the Polish, Czech, French and Low Countries campaigns as well as along the Eastern Front in Russia. After its inherent battlefield usefulness was past, the Panzer III chassis served in a handful of conversions, most notably, the StuG III assault gun. Note: To help the reader along, it is important to note the German designation convention for its military vehicles. The abbreviation Pz.Kpf.W. covers "Panzerkampfwagen" and translates to "armored fighting vehicle". Likewise, the abbreviation Sd.Kfz. covers "Sonderkraftfahrzeug" and translates to "special motor vehicle". Ausf is the general term used to cover "model" or "mark" in showcasing a variant of note. Taking all this into account, the Panzer III can also be known by the designation of Pz.KpfW. III as well as Sd.Kfz. 141 while any model variants are covered in the convention of Ausf. A, Ausf. B, Ausf. C and so on. "Ausf." is the abbreviated form of the word "Ausfuhrung meaning simply "model" or "design". Background In early 1934, the German Army Ordnance Department came to the agreement on the future of their armored corps. It was envisioned that the army would be made up of three companies composed of a light-class of medium tanks backed up by a fourth company composed of a dedicated class of medium tanks with better armor and firepower. The idea then was to develop two such medium tanks tasked with two distinct battlefield roles but were still complementary to the entire German process of waging a mobile land battle. The two tanks became the Pz.Kpf.W. III (Sd.Kfz. 141) and the heavier Pz.Kpf.W. IV medium tanks respectively. The Panzer III would be called to take on the role of tank killer - that is, square off against enemy armor at range - while the Panzer IV would be mainly an infantry support tank. German General Heinz Guderian laid down the specifications for the desired light-medium tank. 1935 saw prototype development contracts issued by the Weapons Department to Daimler-Benz, Krupp, MAN and Rheinmetall-Borsig. The new "light" medium tank would be armed with a more potent 37mm high-velocity main gun armament than her predecessors and supplemented by machine guns - two in the turret as co-axial mounts and a third in a flexible bow mount. The selection of the 37mm armament was a logistical one at this point for German infantry were already using the 37mm anti-tank gun (as the 3.7-cm PaK) in some number by this point. However, the decision to go with the 37mm main gun armament ran into some opposition from senior German officers (including Guderian) who believed that the new tank should be armed with a 50mm/5-cm main gun. As such, the compromise became the fitting of the 37mm gun for the time being, with a special turret ring made to accept a 50mm main gun in the future. The prototype vehicles were evaluated in 1936 with a 15-ton Daimler-Benz submission declared the winner. The First Gun The initial Panzer III armament centered around the high-velocity 3.7-cm Kw.K. L/45 main gun. The weapon was capable of firing armor-piercing (AP) and high-explosive (HE) rounds and proved most effective at close ranges where armor thickness of up to 70mm could be pierced. This value, however, dropped off dramatically at increased ranges. Projectile torque was accomplished through the internal rifling of the gun barrel - a standard practice of all German World War 2 tanks. The Panzer III Ausf. A, Ausf. B, Ausf. C and Ausf. D Daimler-Benz advanced its design and produced the Pz.Kpf.W. III Ausf. A. Power was supplied by a Maybach liquid-cooled gasoline engine of 250 horsepower output. The system featured five large-diameter road wheels to each track side with coil spring suspension. This suspension system was deemed inadequate by the German Army and, as such, further developmental models soon appeared in the Ausf. B, Ausf. C and Ausf. D, each fitting various suspension solutions (Ausf. D also fitted a revised cupola and thicker armor). These three further developments brought about use of eight small road wheels with leaf spring suspension. The hunt for the perfect suspension delayed all full-scale production of the Panzer III. Nevertheless, the German invasion of Poland began on Hitler's schedule, this being September 1st, 1939, with whatever Panzer Is, IIs and limited-quantity IIIs were on hand. A total of 75 Pz.Kpf.W. Ausf. A, Ausf B., Ausf. C and Ausf. D tanks were produced in whole. Combat actions in Poland quickly showed the Panzer III Ausf. B, Ausf. C and Ausf. D to be insufficiently armored for the task at hand. Polish anti-tank guns could penetrate the 15mm-thick steel armor of these early Panzers with relative ease. Coupled with the suspension troubles, these Panzer IIIs faced early retirement and were eventually withdrawn from service before the Invasion of France in May of 1940. By that time, some 349 new Panzer IIIs would be made available to the Wehrmacht. The Panzer III Ausf. E The Pz.Kpf.W. III Ausf. E was developed around a new torsion bar suspension system for its new six road wheel layout (doubled on each track side for an actual total of 24 road wheels). After-action evaluation from engagements during the Polish campaign brought about an increase in armor protection to 30mm thickness along all major structural facings. While this worked well to increase crew and system protection, the added cost in weight increased to 21 tons. The increase led to the selection of a newer and more powerful Maybach powerplant now outputting 300 horsepower. The gun of choice was the 3.7-cm Kw.K. 36 L/46.5 series main gun (though later retrofitted with the 5-cm Kw.K. 38 L/42 series). The German Army Ordnance Office liked what it had and officially cleared the Pz.Kpf.W. Ausf. E for mass production. Ninety-six such vehicles were produced from 1938 through 1939. The Panzer III Ausf. F The Pz.Kpf.W. III Ausf. F was a slightly modified - though similar - version of the Ausf. E with six road wheels to a track side. Ausf. F featured the implementation of cast steel brake ventilation ducts and repositioned final drives along the front hull plate. The main gun was the 3.7cm Kw.K. 36 L/46.5 and (later) the 5-cm Kw.K. 38 L/42 series. The Pz.Kpf.W. III Ausf. F was produced in 435 examples from late 1939 through the mid-way point of 1940. Upon their inception into service, both the Ausf. E and the Ausf. F were the Panzer IIIs of choice for the Invasion of France. The 5-cm Kw.K. L/42 (50mm) Main Gun The original 37mm main gun armament proved inferior from the start, much to the chagrin on the part of senior German Army officials convinced of the type's inadequate power on the modern battlefield as it was. As such, the move to a more powerful 50mm gun was finally enacted with the selection and installation of the 5-cm Kw.K. 39 L/42. The 50mm gun was immediately a more capable component and could fire a broader range of projectiles over the 37mm system it replaced. Despite its upgrade over the original 37mm guns, this 50mm system wasn't Hitler's first choice as the main armament for the new-model Pz.Kpf.W. IIIs (Hitler played a greater role in weapons development as the war progressed, often times to the detriment of the projects). In February of 1941, he explicitly stated that the Pz.Kpf.W. III be armed with the 5-cm Kw.K. 39 L/60, a gun barrel of higher velocity and longer length. The major problem with this requirement was that the Kw.K. 39 L/60 was in the short supply. Additionally, the Ordnance Department believed that their selection of the shorter-barrel 50mm was the right (and better) choice. However, after the opening rounds that was the invasion of the Soviet Union (through Operation Barbarossa), Hitler was actually proven correct. 1,440 Panzer IIIs were fielded in the offensive and the 50mm-armed systems - though excellent against the light fast tanks of the Red Army -proved ineffective against the thickly-armored Soviet T-34 and KV-1 tanks, with reports of 50mm projectiles seemingly bouncing off Soviet turrets and hulls. Shortly thereafter, the longer higher-velocity 50mm gun barrel - the one originally endorsed by Hitler - became standard through the middle of production for the Pz.Kpf.W. III Ausf. J models. All other earlier Pz.Kpf.W. IIIs in circulation also had their main guns retrofitted as such. Conversions to the more lethal gun took place from the end of 1941 through 1943, producing some 2,000 more-capable Pz.Kpf.W. IIIs. By 1942, the old original 37mm main guns were all but non-existent across the war's ever-expanding fronts. The Panzer III Ausf. G The Ausf. G emerged from the Ausf. E and Ausf. F developments. Pz.Kpf.W. III Ausf. G fitted an all-new commander's cupola and a revised driver's vision block. Steel plates of 30mm thickness were added to the existing 30mm structure for vastly improved frontal armor protection and a more powerful engine was introduced to compensate for the added weight. The new steel plate additions proved so effective that they were retrofitted onto preceding Ausf. E and Ausf. F models. The main gun was the 5-cm Kw.K. 38 L/42 series while the second 7.92mm co-axial machine gun was dropped from the turret design. The Ausf. G was produced in 600 examples from early 1940 into 1941. The Ausf. G fought in limited quantity in the invasion of France.