Stunning successes in Poland and France earned the German Wehrmacht a reputation as a modern mechanized juggernaut which employed its armored forces, air power, and artillery in an invincible combination to enable the Blitzkrieg that crushed the armies of two continental powers in shockingly savage and brief campaigns. While that reputation was well-earned, especially after the victory in France in 1940, the reality was somewhat more pedestrian. The highly mobile mechanized forces of the Wehrmacht in 1939-40 represented but a small portion of the German Army, perhaps 10% of the combat forces, and were never more than a minority of the combat forces at hand.
Additionally, in the summer of 1939, Germany’s Panzerwaffe was coming off of a lackluster performance in Spain, and two harrowing, if uncontested, road marches, into Austria in 1938 and into Czechoslovakia in March of 1939, when each time the mechanized columns were plagued by mechanical breakdowns, engine trouble, and fuel resupply issues.
However, the Wehrmacht proved itself to be an impressive learning organization, and rapidly sought to solve the doctrinal and technical problems identified in Spain and Austria and Czechoslovakia in order to make the Panzerwaffe the decisive instrument of maneuver warfare that visionary men such as Heinz Guderian knew it could be. Nowhere is that learning more evident than in the development of the tank guns of the Panzerwaffe. In this post I will track their development from the small-caliber machine-cannon to the famously lethal instruments whose descendants remain in the world’s arsenals today.
A couple of notes on terminology. German is not the easiest of languages to grasp for the uninitiated, and the propensity for long compound words can make figuring out the abbreviations and acronyms a bit of a headache. So let me present a short glossary of terms for easier comprehension. There are other translations of many of these words, but for the purposes of military terminology, these are the most common accepted meanings.
- Panzerkampfwagen- “Armored battle vehicle”, or tank. Abbreviation Pzkw. For simplicity, rather than noting the Panzerkampfwagen Model III, many will use the abbreviation as Pzkw III, and that will be the method used here.
- Ausführung- “Version”. Abbreviated Ausf. Denotes a subtype of a particular model. The Pzkw IV Ausf E differed substantively from Ausf H, even though both emanated from the same basic design.
- Fliegerabwehrkanone- “Anti-aircraft cannon”. Abbreviated FlaK. Which, of course is the name allied airmen gave to all anti-aircraft fire.
- Panzerabwehrkanone- “Anti-tank cannon”. Abbreviated PaK. Often either progenitor or derivative of the tank gun of the same caliber and length, with which there was some shared nomenclature.
- Kampfwagenkanone- “Battle vehicle cannon”. Abbreviated KwK. The tank’s gun, usually the main gun.
- Panzergranate- “Armor grenade”, describing the projectile itself. Abbreviated PzGr. Two projectiles, PzGr 39 and PzGr 40, were developed for a variety of calibers, and while there were further developments in projectile technology, those two variants would remain the vast bulk of ammunition in use. (The PzGr 40 was a tungsten-core projectile, which was generally lighter in all calibers than the concomitant PzGr 39. These tungsten-core projectiles had different ballistic coefficients, resulting in significantly better penetration capabilities at longer effective ranges in the larger calibers.)
- “Caliber” as a measure of tube length. Cannon tube lengths are measured proportionate to the opening at the muzzle. A 7.5cm cannon (75mm wide at the muzzle) that is 43 calibers long has a tube length of 3225mm (75mmx43), or 322.5cm. The longer the tube length, the higher the muzzle velocity, and generally, the greater the penetration capability of the gun. Tube length was designated by the letter “L” followed by a slash and a number. That number represents the number of calibers of length. The above 7.5cm cannon of 43 calibers would be designated “7.5cm L/43”.
The initial efforts of the Reichswehr in tank development had to take place in secret, as tanks were forbidden Germany by the Versailles Treaty. The first such tank was the Panzerkampfwagen I, or Pzkw I, development of which began in 1932, production beginning in 1934. The Pzkw I was a very light tank of only six tons, with thin armor and a pair of 7.92mm MG-13 machine guns in a small turret.
The design was largely built as a training vehicle that could be employed while more suitable designs were developed. Lightly armored and without a tank gun, the Pzkw I ran afoul of Soviet 45mm tank guns in Spain, and was thoroughly obsolete by 1939, though many remained in service in the first years of the war. (The design did provide training opportunity and design/manufacturing experience which would pay off in later and more capable tanks, assault guns, and self-propelled artillery platforms as the war progressed.)
The Pzkw II, incorporating the design lessons of the Pzkw I, was a larger light tank design. It was the first to mount a true cannon, the Rheinmettal-Borsig manufactured 2cm KwK 30 L/55. The KwK 30 fired a 120-gram (4.11oz) PzGr 39 projectile which could penetrate 20mm (0.77 inch) of armor at 100 meters, and 14mm (.55in) of armor at 500 meters. The PzGr 40, a 100 gram tungsten core projectile, could penetrate 49mm and 20mm at 100 and 500 meters, respectively. Not surprisingly, this performance was found to be inadequate when the Condor Legion faced Soviet-built T-26 and BT tanks, whose 45mm guns could penetrate the Pzkw II’s thin armor well past effective ranges of the 2cm KwK 30. Later versions of the Pzkw II, beginning with Ausf J, mounted the slightly improved 2cm KwK 38 L/55.
The harsh lessons from the Spanish Civil War were incorporated into the designs of the next two Wehrmacht tanks, the Pzkw III and IV. The Pzkw III was designed to engage enemy armor, and initial variants (Ausf A through F) mounted the then-lethal 3.7cm KwK 36 L/46.5 cannon. The KwK 36 L/46.5 was a tank-mounted version of the successful 3.7cm PaK 36 L/46.5, and could defeat the front and side armor of the Soviet BT and T-26 tanks at 1,500 meters. Despite the smaller caliber, the 3.7cm KwK 36 was superior to the Soviet 45mm cannon in both armor penetration and range. The 1939 Polish campaign revealed no shortcomings with the 3.7cm gun, as Poland possessed few modern tanks, and none with armor protection that could withstand the KwK 36.
In France, however, the 3.7cm KwK 36 proved unable to penetrate the much heavier armor of the British Matilda I and the French S-35 and Char B1 tanks. Worse was to come. In North Africa, both the Matilda and Valentine proved difficult opponents. In Russia, the 3.7cm KwK 36 was all but worthless against the T-34 and KV tanks in the Red arsenal. An upgrade of the tank main gun was already being developed beginning with Ausf F, that being the 5cm KwK 38 L/42, which was a substantial improvement over the 3.7cm KwK 36. However, it was clear after the first weeks in Russia that the penetration performance of the L/42 was already marginal, and production of the more lethal 5cm KwK 39 L/60-equipped Pzkw IIIs (Ausf J1 and later) soon replaced the L/42-armed vehicles. The L/42-equipped Pzkw IIIs were re-gunned with the newer L/60. The “long-barrel” Pzkw IIIs were capable of defeating all but the heaviest Soviet armor at ranges up to 1,000 meters, and with the PzGr 40, could penetrate the Soviet T-34/76 and KV-1 at 500 meters.
The parallel design of the late 1930s to the Pzkw III was the Pzkw IV medium tank. Much like the American M4 Sherman, the Pzkw IV was conceived as an infantry support tank, and initial variants mounted the short-barreled low-velocity 7.5cm KwK 37 L/24. As the role of the medium tank as an infantry support vehicle was proven less important than that of tank vs. tank combat (assault guns were at least as effective in such an infantry support role), the otherwise excellent Pzkw IV was in desperate need of a tank-killing gun.
Beginning with Ausf “F2” (later called Ausf G), the Pzkw IV began to receive a much more lethal main gun. The 7.5cm KwK 40 L/43 was a considerable improvement over anything in the Wehrmacht arsenal, a tank derivative of the very successful 7.5cm PaK 40. With the larger propelling charge and higher velocity, recoil became a significant issue. Originally, the KwK 40 was fitted with a ball muzzle brake, before being mated with a double-baffle design. Barrel length was increased on the KwK 40 to a 48-caliber tube, improving penetration capability slightly at all ranges. The 7.5cm KwK40 L/43 and L/48 were the most widely employed German tank guns of the war, and proved more than a match for the American Sherman, the British Churchill, and the Soviet T-34/76 and /85 at combat ranges. With upgraded armor, and the long-barreled 7.5cm gun, the Pzkw IV remained a potent tank killer until the end of the war. (Ironically, the last action of the Pzkw IV was in the 1967 Six Day War, when employed by the Syrians against Israeli M50 Shermans armed with a copy of the 7. 5cm KwK42L/70!)
Contrary to its legendary reputation, the most lethal German tank gun for most of the war was not the Pzkw VI Tiger’s vaunted “88” (more on that in a bit), but rather the 7.5cm KwK 42 L/70 of the Pzkw V Panther. Designed to defeat anything on the battlefield, the Panther’s gun fired the PzGr 40/42 projectile at almost 3,700 feet per second, which was capable of penetrating the heaviest armor in the Allied inventory at ranges exceeding 2,000 meters. This included the American M-26 Pershing, the British Centurion, and the Soviet JS-2 heavy tanks. The deadly L/70 would also be produced as a towed anti-tank gun, the 7.5cm PaK 42. (One major difference between the KwK and the PaK versions is that the Panther’s KwK was electrically fired.) The KwK 42 was such an advanced design that the French adapted it as the main gun of the AMX-13, which remained in production until the late 1980s and can be found in a number of the world’s arsenals even today. It was the KwK 42/AMX-13 derived 75mm cannon that equipped many of Israel’s M-50 Super Shermans.
The development in 1941-42 of the legendary Pzkw VI Tiger gave the Wehrmacht a combat vehicle that mounted the vaunted 8.8cm gun, a adaptation of the 8.8cm Fliegerabwehrkanone (FlaK) 18/36 L/56 that had proven so deadly in the anti-tank role in North Africa and Russia. Production began in August, 1942. The massive Henschel-designed 56-ton Pzkw VI Tiger was protected by armor up to 120mm thick, and on the front hull and glacis was proof against anything except close-range (500m) shots by all but the most powerful Allied tank and anti-tank cannon. The Tiger was expensive and complex, but a fearsome tank killer, operating in “heavy tank detachments” (Schwere Panzerabteilung) on both the Eastern and Western Fronts. Tales of handfuls Tigers decimating entire battalions of Soviet tanks with long range shots from the KwK 36 L/56 are legion, and the machine was much feared by Soviet, American, and British crews.
Beginning in January of 1944, improvements to the design of the Tiger began. These included thicker, sloping armor, wider tracks, and the mounting of the massive 8.8cm KwK 43 L/71 cannon (A tank cannon version of the PaK 43 L/71). Production was halted on the earlier Henschel version of the Tiger (Ausfuhrung E), in the spring of 1944 in favor of the improved Ausfuhrung B Königstiger (often called “Tiger II”). At seventy tons, it was the heaviest operational tank of the war. Production was severely interrupted by the Allied air campaign over Germany, and fewer than 500 were built before the end of the war. But while it was in service, as a tank-killer it had no equal. The Königstiger‘s cannon could penetrate an astounding 152mm of armor plate at a 30 degree angle at a range of 2,000 meters. In fact, the L/71 was capable of penetrating the frontal armor of every Allied tank in service at ranges of 2,500 meters or more, well beyond the ability of any Allied tank to successfully engage a Königstiger.
The Königstiger and its 8.8cm KwK 43 L/71 represented the last word in German tank design during World War II. A number of other experimental projects, including super-heavy tanks (E-100) mounting gargantuan 12.8cm cannon, had been in various stages of development, but none ever saw action. (The Jagdtiger, a Königstiger chassis mounting a 12.8 cm PaK 44 L/55 in a non-rotating armored casemate, saw limited service in the last year of the war.)
The history of tank gun design in the Third Reich is a fascinating one. The Wehrmacht found itself well behind in the field of tank main gun design, being outclassed in 1937-38 by Russian and British designs, but by 1943 had more than closed the gap, producing the most lethal and accurate tank killers on the battlefield. Adding to the lethality of the guns and ammunition themselves was the superb quality of German optics. The Leitz sights (Turmzielfernrohr 9 and Turmzielfernrohr 12-series) had wider fields of view than allied counterparts, and contained reticle patterns which aided greatly in range estimation. The level of magnification was generally higher, and lens quality markedly superior to American, British, and Soviet manufacture.
By any standard, to move in just half a decade from a position of marked inferiority to near complete dominance in the design of tank armament is an impressive accomplishment. And that accomplishment is indicative of the German willingness to identify and absorb tactical and technical lessons from the battlefield in the development of newer, more effective weapons and equipment. The legacy of those weapons, and some of the weapons themselves, can still be found on battlefields and in military equipment inventories seventy years after the war.