Self-propelled gun

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The British AS-90 self-propelled guns are examples of modern tracked self-propelled guns. AS-90 self-propelled artillery.JPG
The British AS-90 self-propelled guns are examples of modern tracked self-propelled guns.
SPGs do not have to be necessarily tracked or armoured: the CAESAR howitzer, shown in the photo, is based on a 6x6 truck chassis. CAESAR-openphotonet PICT6026.JPG
SPGs do not have to be necessarily tracked or armoured: the CAESAR howitzer, shown in the photo, is based on a 6×6 truck chassis.

A self-propelled gun (SPG) is a form of self-propelled artillery, and in modern use is usually used to refer to artillery pieces such as howitzers.

Self-propelled artillery Artillery mounted on a vehicle for mobility and protection

Self-propelled artillery is artillery equipped with its own propulsion system to move towards its target. Within the terminology are the self-propelled gun, self-propelled howitzer, self-propelled mortar, and rocket artillery. They are high mobility vehicles, usually based on continuous tracks carrying either a large field gun, howitzer, mortar, or some form of rocket/missile launcher. They are usually used for long-range indirect bombardment support on the battlefield.

Artillery class of weapons which fires munitions beyond the range and power of personal weapons

Artillery is a class of heavy military weapons built to fire munitions far beyond the range and power of infantry's small arms. Early artillery development focused on the ability to breach defensive walls, and fortifications during sieges, and led to heavy, fairly immobile siege engines. As technology improved, lighter, more mobile field artillery cannons developed for battlefield use. This development continues today; modern self-propelled artillery vehicles are highly mobile weapons of great versatility providing the large share of an army's total firepower.

Howitzer Type of artillery piece

A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles over relatively high trajectories, with a steep angle of descent.


Self-propelled guns are mounted on a motorized wheeled or tracked chassis (because of this they are sometimes visually similar to tanks). As such the gun can be maneuvered under its own power as opposed to a towed gun that relies upon a vehicle or other means to be moved on the battlefield. Self-propelled guns are combat support weapons; they are employed by combat support units fighting in support of, or attached to, the main combat units: infantry and armour (tanks). Self-propelled guns are best at providing indirect fire but can give direct fire when needed. It may be armoured, in which case it is considered an armoured fighting vehicle (AFV). Typically, self-propelled guns are more lightly armoured and may not have turrets and their purpose is distinct from that of tanks.

Infantry military service branch that specializes in combat by individuals on foot

Infantry is the branch of an army that engages in military combat on foot, distinguished from cavalry, artillery, and tank forces. Also known as foot soldiers, infantry traditionally relies on moving by foot between combats as well, but may also use mounts, military vehicles, or other transport. Infantry make up a large portion of all armed forces in most nations, and typically bear the largest brunt in warfare, as measured by casualties, deprivation, or physical and psychological stress.

Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire. Aiming is performed by calculating azimuth and inclination, and may include correcting aim by observing the fall of shot and calculating new angles.

Direct fire trajectory of a projectile

Direct fire refers to the launching of a projectile directly at a target within the line-of-sight of the firer. The firing weapon must have a sighting device and an unobstructed view to the target, which means no objects or friendly units can be between it and the target. A weapon engaged in direct fire exposes itself to return fire from the target. This is in contrast to indirect fire, which refers to firing a projectile on a ballistic trajectory or delivering munitions by guided or unguided missiles. Indirect fire does not need a direct line of sight to the target because the shots are normally directed by a forward observer. As such, indirect fire weapons can shoot over obstacles or friendly units and the weapons can be concealed from counter-battery fire.

The greatest tactical advantage in the case of artillery guns is clearly the greater degree of mobility they have compared to towed artillery. Not only is it important in offering military forces greater flexibility, but it is critical in avoiding attack from the enemy (counter-battery fire) by allowing the guns to change position immediately after firing one or more salvos and before their position can be located ("shoot-and-scoot" tactics). A secondary advantage in the case of – even lightly – armoured guns is the increased protection offered to the gun crews.

Counter-battery fire is a battlefield military activity to defeat the enemy's indirect fire elements, including their target acquisition, command and control components. Counter-battery arrangements and responsibilities vary between nations but involve target acquisition, planning and control, and counter-fire. Counter-battery fire rose to prominence in World War I.


Shoot-and-scoot is an artillery tactic of firing at a target and then immediately moving away from the location from where the shots were fired to avoid counter-battery fire.


World War II Soviet ISU-152. Muzei voennoi tekhniki Oruzhie Pobedy, Krasnodar (68).jpg
World War II Soviet ISU-152.
A modern Chinese PLZ-45 self-propelled howitzer built for export. PLZ45155mm Howitzer.jpg
A modern Chinese PLZ-45 self-propelled howitzer built for export.

The first attempts to give artillery a greater degree of manoeuvrability was in World War I. Although mechanical tractors had been used to tow some artillery, most were still towed by horses. The Gun Carrier Mark I was an artillery piece that was transported by and could be fired from a tracked chassis.

World War I 1914–1918 global war originating in Europe

World War I, also known as the First World War or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as "the war to end all wars", it led to the mobilisation of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history. It is also one of the deadliest conflicts in history, with an estimated nine million combatants and seven million civilian deaths as a direct result of the war, while resulting genocides and the 1918 influenza pandemic caused another 50 to 100 million deaths worldwide.

Gun Carrier Mark I

The Gun Carrier Mark I was a British vehicle of the First World War. The gun carrier was designed to transport a 6-inch howitzer or a 60-pounder gun forward soon after an attack to support infantry in advanced positions. Gun carriers were first used in the Battle of Pilckem Ridge during the Third Battle of Ypres. The carriers moved guns and equipment but were used for the rest of the war mainly for carrying equipment and supplies through areas under fire, where porters in the open would have suffered many casualties. The 6-inch howitzer could be fired while mounted, making the Gun Carrier Mark I the first modern self-propelled gun, a weapon capable of independent action and having tactical mobility on the battlefield.

Between the wars, in the development of their armoured warfare tactics, the British put the Birch gun into limited use. It carried an 18 pounder gun on a chassis derived from their then medium tank and as such was able to keep up and cross the same ground as the tanks it was intended to support. As well as use as a field gun, the gun could be elevated sufficiently for use against aircraft.

Birch gun

The Birch Gun was the world's first practical self-propelled artillery gun, built at the Royal Arsenal, Woolwich in 1925.

Self-propelled guns and howitzers

A modern PzH 2000 howitzer of the German Army. PzH2000.Ger.jpg
A modern PzH 2000 howitzer of the German Army.

Self-propelled guns and howitzers are used in the same way as their towed variety, generally for long-range bombardment. Self-propelled artillery can however also include other types of weapons not considered a self-propelled gun, one example of which would be rocket artillery.

Rocket artillery class of rockets used as artillery

Rocket artillery is a type of artillery equipped with rocket launchers instead of the more conventional guns, howitzers, or mortars. Types of rocket artillery pieces include multiple rocket launchers.

Assault guns

Assault guns are large-caliber artillery pieces, meant to support infantry by direct fire with high explosive ammunition.

M109A2 self propelled howitzers of the US 3rd Field Artillery Regiment firing on Iraqi positions during the First Gulf War DS1991.jpg
M109A2 self propelled howitzers of the US 3rd Field Artillery Regiment firing on Iraqi positions during the First Gulf War


See List of self-propelled howitzers


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