Self-propelled gun (SP gun) Horse artillery might be said to be the first SP equipment, given that its purpose was to provide highly mobile artillery support in forward areas using a dedicated power source. More usually, an SP gun is taken to be one mounted on its own automotive system, rather than one designed to be towed. These may be soft-skinned or more usually armoured. The need for such pieces became evident during WW I and early tanks were, in essence, merely SP, direct firing assault guns. It was also clear that indirect fire field artillery also needed an SP capability to keep up and exploit success in a breakthrough battle across shattered terrain.
The first British SP equipment was the experimental gun-carrying tank of January 1917, a tank chassis with a 6 inch gun. The French produced 220 mm pieces mounted on the Renault FT light tank chassis. Recommendations flowing from battlefield experience did not survive long in peacetime. The French inspector general of artillery had suggested that all medium and heavy artillery should be SP, but majority opinion was against him and all development was stopped. The US army developed SP artillery based on the Christie chassis but work on this was halted in 1922. The British army persisted for a time and produced the 18-pounder Birch Gun which was tested on exercise in 1925 with the Experimental Mechanized Force, but most influential opinion was against the SP and there were no further trials after 1930. The essential problem was seen to be one of logistics—how could the weight of ammunition which artillery required be supplied in a fast-moving tank battle? It was also argued that as tank armament became more powerful, tanks did not need artillery support. The British army, like most others, entered WW II with no SP guns of any type. The experience of war rapidly changed perceptions. The French appreciated the value of SP artillery and in 1936 decided to introduce five SP battalions, but when war broke out they had only some experimental equipment.
SP equipment was fielded rapidly once the need became clear. They included families of assault guns, anti-armour guns, field guns, howitzers, and anti-aircraft guns. The British mounted a 25-pounder on a Valentine tank and adopted the Canadian Sexton, based on a medium tank. In 1940, US Gen McNair devised a controversial anti-armour doctrine which was to guide US tank development throughout WW II, but which was eventually found to be flawed. He envisaged the SP tank-destroyer, rather than the tank, as the primary anti-armour system and the most common of these US tank-destroyers was the M10. The Germans' first Panzerjäger was a 47 mm gun on a Mk I tank chassis, but this was followed by the heavier 88 mm Ferdinand Elefant of 1943 and the Hetzer of 1944-5. German SP field artillery included the 105 mm Wespe and the 150 mm Hummel howitzer. The Soviets developed SP artillery as an integral part of their design for offensive armoured operations and placed them under command of the tank forces rather than the artillery. The most notable Soviet systems were the SU-85 and SU-100 dual-purpose tank-hunters which only left Soviet service in 1957. An amphibious SP gun, originally called the Amtank, was developed by the USA, primarily for use in the Pacific campaign. It would open fire from its landing craft at about 4, 374 yards (4, 000 metres) and continue firing while swimming ashore. It would then revert to its indirect fire role with the divisional artillery.
By the 1960s, the tank-hunting role in most armies had been taken over by the tank itself, but SP equipment remained popular in the field artillery where its protection and cross-country performance were well suited to modern armoured warfare. The Soviets introduced a comprehensive family of SP field artillery in the 1970s, including the 122 mm 2S1 and the 152 mm 2S5. For 30 years from the mid-1960s, the US 155 mm M109 was the mainstay of NATO field artillery. Currently this is being replaced by a number of national ventures offering autonomous navigation, automatic loading, burst fire capability, and increased protection.
Bibliography
- Bellamy, C., Red God of War (London, 1986).
- Gabel, C. R., Seek, Strike and Destroy: US Army Tank Destroyer Doctrine in WW II (Fort Leavenworth, 1985).
- Kurowski, F., and Tornau, G., Sturmartillerie 1939-1945 (Stuttgart, 1978).
- Perrett, B., Allied Tank Destroyers (London, 1979).
- Zaloga, S. J., US Tank Destroyers of the Second World War (London, 1985)
— Jonathan B. A. Bailey
