The T-34 was by far the best tank design in World War 2. In addition to having an excellent combination of firepower, armor, mobility, and shape, its superb technical design, which emphasized simplicity and durability, made it possible to mass produce it in enormous numbers, and gave it very high field and combat reliability, two critical attributes which the advanced German tanks lacked. It was the main war winning weapon of Russia in World War 2.

The T-34 was a medium tank which evolved from a series of pre-war Russian light tanks, which were designed for very high speed (53mph with tracks, and over 60mph in good roads without tracks!!) and long travel range, features which made them a formidable weapon for fast advances very deep into enemy territory, but they severely lacked firepower and armor, so they were not suitable as main battle tanks. Some modern wheeled military vehicles armed with powerful anti tank missiles and machine guns can be regarded as more successful descendants of this type of fighting vehicle.

As a result of the need for an all-purpose main battle tank, the T-34 was developed as a medium tank descendant of those fast light tanks, gradually evolving from their superb technical design, but designed to be a capable main battle tank. The T-34 was lower in height (8ft) than German and American tanks, which was better in using the terrain for taking cover and make it a smaller target to hit. It had sloped armor in both the front and side hull and the turret, which made it harder to penetrate, and of course it had a powerful 76mm gun, which was then a large caliber, and sufficiently thick armor. During World War 2 the gun of the T-34 was upgraded to a more powerful long-barrel 76mm gun and later to 85mm gun, to keep up with the advances in German tank guns and armor.

Initial production and deployment of the T-34 was before the German invasion of Russia. Small numbers of T-34 tanks participated in a series of border battles between Russian and Japanese forces in the far East in early 1941, just three months before the German invasion to Russia.

Both the new T-34 tank and Zhukov, who was later Russia's top military commander in World War 2, made their impressive early debut there, in the far East. Both were noticed and reported by the Japanese, but the Germans ignored those reports and were therefore shocked when they met the first T-34 tanks in combat later that year when they invaded Russia. The Germans so appreciated the performance of the T-34 that when the German military discussed the development of their next tank, the Panther, one of the suggested designs was simply a German copy of the T-34.

There were still small numbers of the new T-34 when the invasion began, and the rapid German advancement so deep into Russia, as far as Moscow, forced the Russian industry, which already lost countless factories, to an unprecedented operation of literally moving its entire remaining military industry factories over 1000 miles further East, to Siberia, to avoid losing it to the advancing Germans.

In those newly built factories, Russia's military industry restored and far exceeded its pre-war mass production capacity. The furious motivation of the Russian production workers to stop the terribly cruel German invaders which were more brutal than Russia's own brutal Communist regime, and the desperate draconic measures of the Russian regime itself, in which being late to work in a factory during the war could result in 10 years imprisonment, gave the wartime Russian military industry the high efficiency that Communism never reached before or after World War 2. In wartime Russia, workers and soldiers alike were motivated by the desire to revenge and the fear of draconic punishments, and were paid in food, which soldiers and workers received while the rest of the population starved severely during the war.

The immense production rate of the T-34 was further boosted by the fact that massive American and British material support enabled the Russian war industry to focus all its effort on the production of a small number of main weapon systems, while other greatly needed equipment, such as trucks and jeeps, field rations and even some aircraft types, were supplied in large numbers by the western allies.

So after the initial tremendous defeats in 1941 which cost Russia millions of soldiers and a huge lost territory, since mid 1942 the Russian army was equipped with rapidly increasing numbers of T-34 tanks which matched the German tanks and increasingly outnumbered them.

Since late 1942, in the late stages of the great battle of Stalingrad, and then in the huge tank battle in Kursk in mid 1943, and until the end of the war, T-34 tanks in ever increasing large numbers, outnumbered and crushed the German tanks, and pushed the German invaders all the way back to Berlin, serving as one of the main war winning weapons of World War 2.

The T-34 was a medium tank, weighed 26 tons. It had a crew of four, it had a good speed of 55kmh (34mph) and a range of 115 miles. During the late stages of the war, the Russian army perfected its mobility so much that tanks were sometimes refueled while still driving forward, without stopping, and the Russian infantry used to keep pace with the advancing tanks simply by riding on them from one battle to the next.

Some T-34 tanks are apparently still being used by some military forces even today, and the generations of Russian tanks developed since World War 2, which were produced in vast numbers during the cold war and still used by many armies, are direct descendants of the T-34, the best tank in World War 2.

Before 1939, the most numerous Soviet tanks were the T-26 light tank and the BT series of fast tanks. The T-26 was a slow-moving infantry tank, designed to keep pace with soldiers on the ground. The BT tanks were cavalry tanks, very fast-moving light tanks, designed to fight other tanks but not infantry. Both were thinly armoured, proof against small arms but not anti-tank rifles and 37 mm anti-tank guns, and their gasoline-fueled engines (commonly used in tank designs in the world at these times) were liable to burst into flames "at the slightest provocation" (Zaloga & Grandsen 1984:111). Both were Soviet developments of foreign designs from the early 1930s: the T-26 based on the British Vickers 6-Ton, and the BT tanks based on a design from American engineer Walter Christie.

In 1937, engineer Mikhail Koshkin was assigned by the Red Army to lead a new team to design a replacement for the BT tanks, at the Kharkiv Komintern Locomotive Plant (KhPZ) in Kharkiv. The prototype tank, designated A-20, was specified with 20 millimetres (0.8 in) of armour, a 45 mm (1.8 in) gun, and the new model V-2 engine, using less-flammable diesel fuel. It also had an 8×6-wheel convertible drive similar to the BT tank's 8×2, which allowed a tank to run on wheels without caterpillar track (Zheltov 1999). This feature had greatly saved on maintenance and repair of the unreliable tank track of the early 1930s, and allowed tanks to travel over 85 km/h (53 mph) on roads, but gave no advantage in combat. By then, the designers considered it a needless waste of space and weight (Zaloga & Grandsen 1984:66, 111). The A-20 also incorporated previous research (BT-IS and BT-SW-2 projects) into sloped armour: its all-round sloped armour plates would be more likely to deflect armor-shells than perpendicular armour.

Koshkin convinced Soviet leader Joseph Stalin to let him develop a second prototype, a more heavily armed and armoured "universal tank" which could replace both the T-26 and the BT tanks.[4] The second prototype Koshkin named A-32, after its 32 millimetres (1.3 in) of frontal armour. It also had a 76.2 mm (3 in) gun, and the same model V-2 diesel engine (Zaloga 1994:5). Both were tested in field trials at Kubinka in 1939, and the heavier A-32 proved to be as mobile as the A-20. A still heavier version of the A-32 with 45 millimetres (1.8 in) of front armour and wider tracks was approved for production as the T-34. Koshkin chose the name after the year 1934 when he began to formulate his ideas about the new tank, and to commemorate the decree expanding the armoured force and the appointment of Sergo Ordzhonikidze to head tank production (Zaloga 1994:6).

Two prototype T-34s were completed in January 1940, and underwent a gruelling 2,000-kilometre (1,250 mi) drive from Kharkiv to Moscow for a demonstration for the Kremlin leaders, to the Mannerheim Line in Finland, and back to Kharkiv via Minsk and Kiev, in April and May (Zaloga 1994:6). Some drivetrain shortcomings were identified and corrected (Zaloga & Grandsen 1983:6). Resistance from the military command and concerns about high production cost were finally overridden by anxieties about the poor performance of Soviet tanks in Finland and the effectiveness of Germany's Blitzkrieg in France, and the first production tanks were completed in September 1940, completely replacing the production of the T-26, BT, and the multi-turreted T-28 medium tank at the KhPZ. Koshkin died of pneumonia at the end of that month (exacerbated by the drive from Kharkov to Moscow), and the T-34's drivetrain developer, Alexander Morozov, was appointed Chief Designer.

The T-34 had the coil-spring Christie suspension of the BT, but dispensed with the weighty but ineffective convertible drive. It had well-sloped armour, a relatively powerful engine, and wide tracks. The initial version had a 76.2 mm gun, and is often called T-34/76 (originally a World War II German designation). In 1944 a second major version began production, the T-34-85 (or T-34/85), with a larger turret mounting a larger 85 mm gun.

The T-34 posed new challenges for Soviet industry. It was the most heavily armoured medium tank produced to that point, and subassemblies originated at several plants: Kharkov Diesel Factory No. 75 supplied the model V-2 engine, Leningrad Kirovsky Factory (former Putilov works) made the original L-11 gun, and the Dinamo Factory in Moscow produced electrical components. Tanks were initially built at KhPZ No. 183, in early 1941 at the Stalingrad Tractor Factory (STZ), and starting in July shortly after the German invasion at Krasnoye Sormovo Factory No. 112 in Gorky. There were problems with defective armour plates, however (Zaloga 1983:6). Due to a shortage of new V-2 diesel engines, the initial production run from the Gorky factory were equipped with the BT tank's MT-17 gasoline-burning aircraft engine, and inferior transmission and clutch (Zheltov 2001:40–42). Only company commanders' tanks could be fitted with radios; such radios were expensive and in short supply. The L-11 gun did not live up to expectations, so the Grabin design bureau at Gorky Factory No. 92 designed a superior F-34 76.2 mm gun. No bureaucrat would approve production, so Gorky and KhPZ started producing the gun anyway; official permission only came from Stalin's State Defence Committee after troops in the field sent back praise for the gun's performance (Zaloga & Grandsen 1984:130).

There was political pressure from conservative elements in the army to redirect resources into building the older T-26 and BT tanks, or to cancel T-34 production pending completion of the more advanced T-34M design. This political pressure was brought to bear by the developer of the KV-1 and IS-2 tanks which were in competition with the T-34. Political pressure between designers and factories producing different tanks to meet the same requirements continued much later post war, including a period when the T-55, T-64 and T-72 were all in production at different factories with differing political patrons on the supreme council of the USSR (Armour Magazine, "Why Three Tanks" July-August 1998). Germany's surprise attack against the Soviet Union in June 22, 1941 (Operation Barbarossa) forced the Soviet Union to freeze further development, and shift into full production of tanks.

Germany's fast advances forced the monumental evacuation of tank factories to the Ural mountains. KhPZ was re-established around the Dzherzhinski Ural Railcar Factory in Nizhny Tagil, renamed Stalin Ural Tank Factory No. 183. The Kirovsky Factory was evacuated just weeks before Leningrad was surrounded, and moved with the Kharkov Diesel Factory to the Stalin Tractor Factory in Chelyabinsk, soon to be nicknamed Tankograd ('Tank City'). Voroshilov Tank Factory No. 174 from Leningrad was incorporated into the Ural Factory and the new Omsk Factory No. 174. The Ordzhonikidze Ural Heavy Machine Tool Works (UZTM) in Sverdlovsk absorbed several small factories. While these factories were relocating at record speed, the industrial complex surrounding the Stalingrad Tractor Factory produced forty percent of all T-34s (Zaloga & Grandsen 1983:13). As the factory became surrounded by heavy fighting in the Battle of Stalingrad, the situation there grew desperate: manufacturing innovations were necessitated by material shortages, and stories persist that unpainted T-34 tanks were driven out of the factory into the battlefields around it (Zaloga & Sarson 1994:23). Stalingrad kept up production until September 1942.

Barring this interruption, the only changes allowed on the production lines were to make the tanks simpler and cheaper to produce. New methods were developed for automated welding and hardening the plate, including innovations by Prof. Evgeny Paton.[5] The design of the 76.2 mm F-34 gun Model 1941 was reduced to 614 parts, compared to the earlier model's 861 (Zaloga & Grandsen 1984:131). Over two years, the production cost of the tank was reduced from 269,500 rubles in 1941, to 193,000, and then to 135,000 (Zaloga & Grandsen 1984:131). Production time was cut in half by the end of 1942, even though most experienced factory workers had been sent to the field and replaced by a workforce consisting of 50% women, 15% boys, and 15% invalids and old men. At the same time T-34s, which had been "beautifully crafted machines with excellent exterior finish comparable or superior to those in Western Europe or America", were much more roughly finished, although mechanical reliability was not compromised (Zaloga & Grandsen 1983:17).

In 1942, a new hexagonal turret design derived from the abandoned T-34M project entered production, improving the cramped conditions, and eventually adding a commander's cupola for all-round vision. Limited rubber supplies led to the adoption of steel-rimmed road wheels, and a new clutch was added to the improved five-speed transmission and engine.

After German tanks with the superior long 75 mm (2.95 in) gun were fielded in 1942, Morozov's design bureau began a project to design an advanced T-43, aimed at increasing armour protection, while adding modern features like torsion-bar suspension and a three-man turret. The T-43 was intended to be a universal tank to replace both the T-34 and the KV-1 heavy tank, developed in direct competition with a Chelyabinsk heavy tank design bureau's KV-13 project. (Zaloga et al 1997:5)

In 1943 the Soviets encountered the new German Tiger and Panther tanks. Experience at the Battle of Kursk and reports from front-line commanders indicated that the T-34's 76.2 mm gun was now inadequate. An existing 85 mm (3.3 in) antiaircraft gun was identified which was effective against the new German tanks, and could be adapted to tank use (Russian Battlefield 1998b). Unfortunately, the T-43 prototype's heavier armour was still not proof against the Tiger's 88 mm gun, and its mobility was found to be inferior to the T-34's, even before installing a heavier 85 mm gun. Although it shared over 70% of its components with the T-34, a commitment to manufacturing it would have required a significant slow-down in production. (Zaloga et al 1997:5)

In consequence the T-43 was cancelled, and the Soviet command made the difficult decision to retool the factories to produce a new model of T-34 with a turret ring enlarged from 1,425 mm (56 in) to 1,600 mm (63 in), allowing a larger turret to be fitted. The T-43's turret design was hurriedly adapted by V. Kerichev at the Krasnoye Sormovo Factory to fit the T-34 (Zaloga 1984:166). The resulting new T-34-85 tank had a much superior gun and finally, a three-man turret with radio (which had previously been in the hull). Now the commander needed only to command the tank, leaving the operation of the gun to the gunner and loader.

Overall production slowed down somewhat while the new tank started its production run. Although a T-34-85 was still not a match for a Panther, the improved firepower made it much more effective than before. The decision to improve on the existing design instead of tooling up for a new one allowed the Soviets to manufacture tanks in such numbers that the difference in capabilities could be considered insignificant. In May 1944, the Wehrmacht had only 304 Panthers operating on the Eastern Front, while the Soviets had increased T-34-85 production to 1,200 tanks per month (Zaloga et al 1997:6).