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modified: Nov 10, 2012
The T-26 was a Soviet light tank that was used from the 1930s until World War II. Its design is based upon the British Vickers-Armstrong 6-ton E light tank. The T-26 was intended to execute the first stage of the Soviet's Deep Battle concept by supporting the infantry during breakthrough operations. The T-26 is one of the most-produced tanks in history with about twelve thousand units manufactured. It was the most significant tank in the Spanish Civil War. It has also seen service in the Winter War, and the Battle of Khalkhin Gol.

Development History
The Vickers-Armstrong 6 ton E light tank was bought on May 28, 1929 by the Directorate of the Mechanization of the Red Army (UMM). The first tanks arrived in the Soviet Union in 1930. They were examined by the staff of the Mechanization and Motorization Faculty of the Dzherzhinskiy Artillery Academy in Leningrad. Soviet designers built two improved prototypes based on the Vickers designated TMM-1 and TMM-2. About twenty TMM tanks were built. The TMM-1 and TMM-2 derivatives were competitively tested with the Vickers at Kubinka testing ground.

On February 13, 1931, the Revolutionary War Council (RVS) ordered mass production of the Vickers under the designation T-26. A new design team, OKMO (Opytniy konstruktorsko mekhanicheskiy otdel: Experimental Design Mechanical Section) headed by N. Barykov and S. Ginzburg was formed at the Bolshevik Factory to make some crucial changes before mass production began. The first large-scale public display of T-26 took place on November 7, 1931.

The T-26 Model 1931 was twin-turreted. 120 T-26s were completed in 1931. The standard model had a 7.62mm DT machine gun in each turret. There was also a command tank version designated the T-26TU (Tank Upravleniya) with a 37mm gun replacing the DT machine gun in the right turret. The T-26TU Model 1931 was the first Soviet tank to have a standardized vehicular radio transmitter with a clothes-line antenna. A few T-26TUs were equipped with the 37mm gun PS-2 Model 1930 which had a longer barrel. There was also a proposal to mount 45mm guns on the T-26 which was abandoned in favor of a single turreted version of the T-26. The T-26s built in late 1932 had welded turrets instead of riveted ones.

The T-26 was powered by the Armstrong-Siddeley gasoline engine which was renamed GAZ T-26. It allowed the T-26 to attain a road speed of 32km/h and range of 140km. Although engine design modifications were conducted between 1931 and 1941, they yielded small improvements. The engine's output increased from 67kW to 72kW.

The total production of the T-26 and its variants in 1932 was 1,032.

T-26 Model 1933
The twin-turret design of the T-26 limited combat effectiveness. The two gunners' seats had to be manually rotated. Turret traverse was also restricted to 265°.

In 1933, the right turret of the T-26 was removed to create a single-turret tank. However, the 37mm German Rheinmetall was difficult to load in the confined space. In addition, the turret ring was susceptible to fracture from the powerful gun recoil.

In 1932, the Bolshevik Factory design bureau and its counterpart at the KhPZ were ordered by the UMM to coordinately build a standard turret for the 45mm Model 1932 gun. The first standard turret built under this order was mounted on a small batch of T-26 Model 1933 and the early BT-5 Model 1933 tanks. A modified turret with a larger rear bustle and two roof hatches became the standard on the rest of the T-26 Model 1933, BT and T-35 tanks.

Because of the large tank production requirements, work on the T-26 was expanded to Zavod Nr. 174 (K. E. Voroshilov) and Red Putilov Works among other factories. The T-26 Model 1933 was the most widely produced tank of the Soviet Union before and early in the Second World War. About 5,500 T-26 Model 1933 were built up to 1937.

The last batch of T-26 Model 1933, produced in 1935 and 1936, had two more DT machine guns. One was an anti-aircraft machine gun mounted on a new circular roof hatch while the other was installed in a ball-socket in the rear of the turret for use against infantry.

Some T-26s took part in the conflict between Manchuria and Mongolia that occurred between 1934 and 1935. Reports showed that rivets in the T-26s came free when the outer surface of the tank was hit by machine gun fire with sometimes lethal results to the crew. Tukhachevskiy ordered the production of the T-26s to stop until a solution was determined. After that point, Soviet tank armor was welded instead of being riveted.

There were two kinds of mantlets used on the T-26 Model 1933. One was drop-forged and the other was made up of welded parts.

The T-26 Model 1933 with radios had a distinctive horseshoe antenna. Although there was a proposal to equip all T-26 Model 1933s with radios, only a few tanks actually had them due to a lack of resources. These tanks, sometimes called the T-26TU Model 1933 were used by platoon and company commanders.

The T-46 was an effort to use the Christie suspension on the T-26. After the T-46 project was unsuccessful, the design team of Ginzburg focused on modernizing the T-26.

T-26S Model 1937
The new modernized version was designated the T-26S Model 1937. It had a thicker 25mm frontal armor. Turret armor was also thicker and sloped. In addition, stabilization of the tank gun in one axis was one of the many improvements. Further modifications were conducted on the T-26S including a new turret with a new cast or drop-forged forward section for easier assembly.

In 1939, the hull was redesigned with a new, wider and better armored upper superstructure that had sloped sides. The new hull provided an increased volume for fuel and ammunition storage. This variant was produced until 1940. Specialized variants of the T-26 were built until 1941.

The T-26S was of welded construction throughout. It was equipped with a rod antenna instead of the frame type. Some of the T-26B-2s were upgraded with the new turret without the rear machine gun.

The performance of the T-26S in the Winter War showed that the tank was thinly armored for anti-tank guns and rifles. Plates were added to some T-26S which increased their armor to 50mm. These variants were designated the T-26E (E - s ekranami, with applique).

While the OKMO was improving the T-26, a design team at the Stalingrad Tractor Factory (STZ) was also given a similar task. In 1938, a prototype of the T-25 was built by STZ incorporating a Christie suspension on a T-26. The suspension was too complicated for mass production and a simpler version named the ST-25 underwent trials. At this point however, OKMO was developing a new infantry tank that was later called the T-50.

Combat History
The T-26 took part in the Spanish Civil War, the Winter War, and the Soviet-Japanese Border Wars.

During the Spanish conflict, the T-26 was an effective tank. During the attack on Sesena on October 29, 1936, the 1st Battalion T-26s were able to penetrate Nationalist defenses, shoot up positions in the village, overrun an artillery battery, and destroy two CV 3/35 tankettes. The 45mm gun of the T-26 asserted the tank's superiority over Nationalist tanks and those of their allies.

However, the T-26 suffered from lack of coordination with Republican infantry forces. As a result, the tank was left vulnerable to counterattacks and artillery.

During the battles of Lake Khasan and Khalkhin Gol, the T-26 was used en masse in coordination with supporting arms. The Japanese forward defenses were overwhelmed by infantry with the support of the T-26's 45mm firepower.

In all three conflicts, heavy losses were experienced due to 15mm frontal and 6mm side armor which was vulnerable to new anti-tank weapons and direct artillery fire. During the Jarma River fighting in Spain, Soviet strength was diminished by 40% due to 37mm anti-tank gunfire. In the Winter War, the lack of artillery and infantry support resulted heavy casualties.

During the WWII German offensive in June 1941, the T-26 45mm gun was able to destroy all German armored vehicles it faced except for the Panzerkampfwagen IV. However, many T-26s were lost because of gearbox problems and clutch failures.

Flamethrower Variants
Several flamethrower tanks were developed based on the T-26. They were OT-26, OT-130, OT-133, and OT-134. These tanks were originally called KhT (Химический Танк, Khimicheskiy Tank, chemical tank). However after WWII, the abbreviation OT (Огнеметный Танк, Ognemetniy Tank, flame-throwing tank) became common.

The great disadvantage of the flamethrower tanks was that they did not retain their original turret guns. Therefore, they were vulnerable once their flame fuel run out.

Other Variants
Another variant was the ST-26 (Saperskiy Tank, Engineer tank) that carried a 7m long bridge to cross narrow gaps or obstacles. A few were built and they were used by tank units from 1934 to 1938.

Variants of the T-26 include the T-26A which was an artillery support tank with a larger turret derived from the T-28. It was armed with a 76.2mm Model 27/32 howitzer. As the turret was too heavy for the chassis, only a few were built.

Efforts were also made at developing amphibious versions of the T-26. In 1934, K. Sirken developed a method with rubber sealing and a telescopic 280cm air tube. Trials completed in 1935 were encouraging. Prototypes participated in the Leningrad military district maneuvers of 1937. A small batch were built under the designation, T-26PKh (PKh - Podvodnogo Khoda: Mobile Underwater). An attempt was made in 1935 to equip a T-26 with pontoons for swimming. The prototype had a speed of 3.5km/h but the pontoons proved to be bulky and vulnerable. The project was dropped.

Other unsuccessful variants include two anti-mine prototypes, one using a roller system, and the other chain flails. No series production of neither version was undertaken. There were some self-propelled gun derivatives of the T-26.

References: OW, RTWW2, STCV