Tanks of The Interwar Period - General Developments

General Developments

The final tank designs of 1918 showed a number of trends. The US and British produced the Mark VIII tank. The pinnacle of the rhomboid design, the 34-foot-long (10 m), 37-ton machine was powered by a 300-hp (224 kW) V-12 engine and capable of 7 mph (11 km/h) cross-country. However, the Renault FT set the pattern for almost all tanks that have followed it; these tanks generally had lower track profiles, more compact hulls, and mounted their weapons in turrets.

Worldwide, many sizes of tank were considered, and a lot of development effort went into light tanks that would be useful primarily against infantry or for colonial police-type work. The worldwide economic difficulties of the 1920s and 1930s led to an increased emphasis on light tanks also, since they were so much cheaper than medium or heavy tanks. However, the Spanish Civil War showed that tank-versus-tank engagements and tank-versus-towed antitank gun engagements would now be a major consideration. It became clear that future tanks would need to be heavily armoured and carry larger guns. Tank shape, previously guided purely by considerations of obstacle clearance, now became a trade-off, with a low profile desirable for stealth and weight savings.

In Britain, military opinion was divided on the future of tank warfare. J.F.C. Fuller was convinced that only the tank had a future on the battlefield. Basil Liddell Hart foresaw a war where all arms, infantry, tanks and artillery, would be mechanised, resembling fleets of 'land ships', and experiments in these fields did take place but were not adopted. Liddell Hart would be proved right, but it would not be for sixty years that even the wealthiest countries could make his ideas a reality.

In the U.S., J. Walter Christie developed a series of fast tanks, based on his revolutionary Christie suspension system. This was combined with very high power-to-weight ratios achieved by fitting large aircraft engines in his tanks. Although his prototypes were capable of very high speeds, and in some cases designed to be air transportable, disputes with the Ordnance and a high price (compared with what the US military was willing to pay) meant they were never produced in the USA. Christie's prototypes were however purchased by the Soviet Union, and were to be developed into the BT tanks and eventually, on the eve of World War II, the famous T-34. The BT series in turn influenced the British cruiser tank designs such as the A-13 Cruiser Mk IV, Crusader, and others.

Today it may be difficult to understand why the tank idea found such resistance from the leadership of several armies. Part of the explanation is that the entire automotive industry was in its infancy. Tanks were rightly considered unreliable, troublesome equipment as late as the early 1930s. Weak engines, poor transmissions, and fragile, short-life tracks contributed to this reputation. The otherwise-incomprehensible resistance to tanks from 'traditional' military leadership can be partly understood in this light; a tank battalion that loses most of its vehicles due to mechanical failure on a 50-mile movement is not a reliable asset in combat. The international success of the Vickers six-ton tank is due more to its high reliability than any brilliance in the design. However, as the decade passed, engines, transmissions and tracks all improved. By the beginning of WWII, reliable engines and transmissions, as well as high-speed suspension designs were all available. For example, in 1940, two prototype T-34 tanks completed a gruelling two thousand-kilometre test run by members of its design team, from Kharkov to Moscow, Smolensk, Kiev, and back. The USA, with its huge automobile industry, led the world in high-reliability designs by the beginning of WWII.

A final trend in the between-the-wars period was changes in manufacturing methods. France pioneered the use of very large castings to form gun mantlets, turrets and eventually, with the S-35, entire tank hulls. The widespread use of casting was copied by the US and USSR, and to a lesser extent in the UK. Casting enables the fast manufacture of ballistically well-shaped components. Germany never made much use of large cast components, limiting casting to smaller items such as mantlets. Welding gradually replaced riveting and bolting as a means of fastening rolled armor plate together. Rivets can shear off when struck by enemy fire, resulting in additional crew casualties. Germany and the USSR led the way with welding, although the US followed closely. Riveting and bolting remained in use in some countries such as Hungary, Japan, and Italy, and to a lesser extent in Great Britain right to the end of WWII. Finally, the US and USSR led the way in rationalizing designs for fast production, eliminating unnecessary components or manufacturing steps that added little value. In contrast, French and German pre-war (and even wartime) tanks often incorporated features that added cost or manufacturing complexity out of proportion to their combat value.