The first instalment of this series on the self-propelled gun delves into history and traces its origins.

Any gun mounted on a motorised, wheeled or tracked chassis is called a self-propelled gun (SPG). These are usually used for longrange direct or indirect fire support on the battlefield. In the past, self-propelled artillery has included direct fire vehicles, such as assault guns and tank destroyers. However, modern self-propelled artillery vehicles are generally lightly armoured, too light to survive in direct-fire combat, and superficially resemble tanks. These protect crews against shrapnel and small arms.

The key advantage of self-propelled over towed artillery is that it can be brought into action much faster—an ability especially useful in mobile warfare. Conversely, towed artillery was and remains cheaper to build and maintain. It is also lighter and can be taken to places that self-propelled guns cannot reach. So, despite the advantages of the self-propelled artillery, towed guns remain and will continue to remain in the arsenals of modern armies.

Looking back
The history of self-propelled guns can be traced back to the Thirty Year’s War in the early 17th century when Horse Artillery, considered to be the precursor of the selfpropelled artillery, came into existence. Light field guns were towed by crew mounted horses. The gunners were trained to quickly dismount, deploy the guns and provide instant fire support to cavalry and act as a flexible reserve. The Russian army organised small units of horse artillery, composed of only lighter 3- and 2-lb guns, distributed among cavalry formations in the early 18th century. They inflicted serious losses to Prussian units in the Seven Years’ War.

Russian artillery inspired Frederick the Great to organise the first regular horse artillery unit in 1759. Other nations quickly realised the capability of the new arm and by the start of the French Revolutionary Wars in 1790s, Austria, Hannover, Russia, France, England and Sweden had all formed regular units of horse artillery. The arm was employed throughout the Napoleonic Wars and remained in use throughout the entire 19th century and into the first half of the 20th century, when advances in weapon technology finally made it obsolete.

First World War
Seen in 1917 during the First World War the first self-propelled gun was Gun Carrier Mark I. It was based on the British Mark I Tank and carried a heavy field gun. The gun could either be fired from the vehicle or removed from it and set up on the ground. In effect, the carrier replaced the use of a separate horse team or internal combustion engine powered artillery tractor.

The next major advance was the Birch Gun developed by the British for their motorised warfare experimental brigade after the end of the First World War. This mounted a field gun, capable of both the usual artillery trajectories and high angle anti-aircraft fire, on a tank type chassis. It was designed and built to support an all arms team capable of operating alongside the tanks.

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