Vickers 6-ton
The Vickers 6-ton tank or Vickers Mark E, also known as the "Six-tonner" was a British light tank designed as a private project at Vickers. It was not adopted by the British Army, but was picked up by many foreign armed forces. It was licensed by the Soviet Union as the T-26. It was also the direct predecessor of the Polish 7TP tank. History. The first Mark E was built in 1928 by a design team that included the famed tank designers John Valentine Carden and Vivian Loyd. The hull was made of riveted steel  plates, thick at the front and over most of the turrets, and about thick on the rear of the hull. The power was provided by an Armstrong Siddeley engine of (depending on the version), which gave it a top speed of on roads. The Horstmann suspension used two axles, each of which carried a two-wheel bogie to which a second set of bogies was connected with a leaf spring. Upward movement of either set of bogies would force the other down through the spring. This was considered to be a fairly good system and offered better than normal cross -country performance although it could not compare with the contemporary Christie suspension. High strength steel tracks gave over of life which was considerably better than most designs of the era. The tank was built in two versions: The Type B proved to be a real innovation: it was found that the two-man turret dramatically increased the rate of fire of either weapon, while still allowing both to be fired at the same time. This design, which they referred to as a "duplex mounting", became common on almost all tanks designed after the Mark E. The British Army evaluated the  Mark E, but rejected it, apparently due to questions about the reliability of the suspension. Vickers then started advertising the design to all buyers, and soon received a trickle of orders eventually including the USSR, Greece, Poland, Bolivia, Siam, Finland, Portugal, China and Bulgaria. Thailand purchased 36 Vickers Medium Dragon Mark IVs, and QF 2-pounder naval guns were added to turn them into self-propelled guns used in the 1940-41 Franco-Thai War. Vickers built a total of 153 (the most common figure) Mark Es. Experience with the Polish machines showed that the engine tended to overheat due  to poor airflow over the air-cooled engine. This was addressed by the addition of large air vents on either side of the hull. For a new Belgian order the design was modified to use the Rolls-Royce Phantom II water-cooled engine instead. This engine would not fit in the rear, and had to be mounted along the left side of the tank, requiring the turret to be moved to the right and rearward. One example of the resulting "Mark F" was tested by Belgium, but rejected. Nevertheless, the new hull was used, with the older engine, in the  sales to Finland and Siam. The Mark E was also developed as a cargo vehicle, and purchased by the British Army in small numbers as artillery tractors to haul their large BL 60-pounder () field guns. Twelve were ordered by the Army as the "Dragon, Medium Mark IV", while China purchased 23 and India 18. Poland purchased 50, and also licensed it for the local production, but only put together 38 out of the 50, using the unassembled 12 for spare parts. The Poles modified their vehicles with larger air intakes, their own machine guns, 360-degree Gundlach periscopes, and  five or more with added two-way radios, before deciding to make their own tank that would address the shortcomings of the original Vickers design. This resulted in the 7TP, which was nearly 10 tons in weight. The Poles also, besides the aforementioned telescope, added a liquid-cooled diesel engine as well as better armour protection, better ventilation, two-way radios, a Polish version of the Bofors anti-tank gun, and a bigger crew compartment. Out of 38 original two-turreted tanks, 22 were later converted to single turret version with a modified turret and the main gun (Type B  standard). The tanks were in bad shape by 1939 because they were used in the training units over a period of five years. However, they did perform well and better than the Renault R35, amongst others, as part of the Polish 10. Cavalry Brigade during the Invasion of Poland in 1939. The Soviets were also happy with the design and licensed it for production. However, in their case local production started as the T-26, and eventually over 12,000 were built in various versions. The Soviet early twin-turret T-26s had 7.62 mm (0.3 in) DT machine guns in each turret , or a mix of one machine gun turret and one 37 mm gun turret. Later, more common versions mounted a gun and two DT machine guns. The final versions of the T-26 had welded construction and, eventually, sloped armour on the hull and turret. Because the T-26 was in such wide use and was a reliable platform, a variety of engineer vehicles were built on the chassis, including flamethrowers and bridgelayers. A novel radio-controlled demolition tank was built on the T-26 chassis also. During the Spanish Civil War the Soviet Union sent the T-26 to the Republican Army. The  Italians, after suffering losses from Republican T-26s during the battle of Guadalajara (1937), captured some of these tanks which served as models for their M11/39 and M13/40 medium tanks. In 1939, during the Soviet-Finnish Winter War, the Finnish armoured forces consisted of around thirty-two obsolete Renault FT tanks, some Vickers-Carden-Lloyd Mk. IVs and Model 33s, which were equipped with machine guns, and 26 Vickers Armstrongs 6-ton tanks. The latter had been re-equipped with 37 mm Bofors AT-guns after the outbreak of the war. Only 13 of these tanks managed to get to the  front in time to participate in the battles. At the Battle of Honkaniemi on 26 February 1940, the Finns employed their Vickers tanks for the first – and only – time against Soviet armour during the Winter War. The results were disastrous. Of the thirteen available Finnish Vickers 6-ton tanks only six were in fighting condition and able to participate in the first assault on the Soviet lines – to make matters worse, one of the tanks was forced to stop, unable to cross a wide trench. The remaining five continued onwards a few hundred metres but ran into dozens of Soviet  tanks in the village of Honkaniemi. The Finnish tanks managed to knock out three Soviet tanks but were soon themselves knocked-out. In the skirmishes that followed, the Finns lost two more Vickers tanks. In 1941, the Finns rearmed their Vickers 6-ton tanks with Soviet 45 mm guns and re-designated them as "T-26Es". These tanks were used by the Finnish Army during the Continuation War. Nineteen rebuilt Vickers tanks, along with 75 T-26s continued in Finnish service after the end of the Second World War. Some of these tanks were kept as training tanks until 1959, when they  were finally phased out and replaced by newer British and Soviet tanks. See also. Comparable vehicles. Note: Vehicles armed with machine guns are only comparable to the "A" variant.