Self-propelled artillery

• 1. Introduction

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  Self-propelled artillery is one of those weapons categories that quietly reshaped how armies fight, not by replacing the cannon, but by giving it legs. The idea seems straightforward enough: put the gun on a vehicle so it can drive itself to where it needs to be. But the consequences of that design choice ripple through two centuries of warfare, from camels carrying swivel guns across the rugged Iranian plateau to computerized howitzers that can fire a salvo, vanish before the enemy responds, and show up somewhere else entirely.

  What separates self-propelled artillery from a tank? What separated it from towed artillery in the moments that mattered most? And how did a mechanical engineer named Hauptmann Alfred Becker, improvising in the field with captured British tanks, help set the template for the most-produced armored vehicle Germany built in World War II? Those are the threads this documentary follows.

• 2. Camels and Horse Guns

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  Before there were tracked vehicles, there was the zamburak: a small swivel gun strapped to the back of a camel, fired from the saddle. The Islamic gunpowder empires relied on it, particularly those of Iran, because heavy cannons simply could not be moved efficiently across the rugged Iranian plateau. The zamburak was not elegant, but it worked, and it represents the same governing logic that would drive every generation of self-propelled artillery that followed: get the gun where a wheeled or horse-drawn carriage cannot easily go.

  Horse artillery carried a different version of that logic into European warfare during the Thirty Years' War. Crews rode into battle alongside light field guns, dismounted, deployed their weapons, and provided instant fire support to cavalry. The Russian army formalized small units of horse artillery among their cavalry formations in the early 18th century. Armed with only 2- and 3-pound guns, these units still inflicted serious losses on Prussian forces during the Seven Years' War. That result prompted Frederick the Great to organize the first regular horse artillery unit in 1759. By the 1790s, when the French Revolutionary Wars began, Austria, Hannover, Portugal, Russia, France, Great Britain, and Sweden had all followed. Horse artillery remained in service well into the first half of the 20th century, when advances in weapons technology finally made it obsolete.

• 3. The First Tracked Guns

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  The British Gun Carrier Mark I holds the distinction of being the first tracked self-propelled gun ever fielded in combat. It appeared in 1917 during World War I, built on the chassis of the British Mark I tank, and it carried a heavy field gun that could either be fired from the vehicle or lifted off and set up in the conventional way. In practical terms, it replaced what had previously required a horse team or a separate powered artillery tractor.

  Just over a year before the Mark I entered the field, Italy had already put a wheeled heavy self-propelled gun into service. The 102/35 su SPA 9000 entered service in September 1915 and became the most produced self-propelled gun of World War I, with more than 100 units built. It earned praise for its ability to reposition quickly and came with a sophisticated logistic support system that included more than 7 support vehicles per gun. Between the wars, the British developed the Birch gun for their experimental motorised warfare brigade: it mounted an 18-pounder field gun on a Vickers medium tank chassis and could fire at both standard artillery trajectories and high-angle anti-aircraft targets. The Red Army experimented with truck- and tank-mounted artillery in the same period but produced none of its designs in quantity.

• 4. Improvisation Under Fire

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  At the outbreak of World War II, virtually all artillery was still being towed by tractors or horses. German Blitzkrieg doctrine demanded fire support for fast-moving armoured units, but in Poland and France that role was handled by Junkers Ju 87 Stuka dive-bombers acting as flying artillery. Conventional towed howitzers followed behind.

  Hauptmann Alfred Becker changed that calculus from the ground up. A mechanical engineer and battery captain in the 227th Infantry Division, Becker mounted his 10.5 cm leFH 16 howitzers onto the chassis of captured British Vickers Mk.VI light tanks to keep his guns moving with the armoured advance. His improvised vehicle, the 10.5 cm leFH 16 Geschützwagen Mk VI 736 (e), was the direct forerunner to the German Wespe and Hummel field guns.

  British designers took a similarly improvised early route, carrying guns on trucks in a technique the British Army called portee. The first dedicated British design, named Bishop, put the 25-pounder gun-howitzer on a Valentine tank chassis but in a mounting that severely limited the gun's performance. It was eventually replaced by the more capable Sexton. Germany also repurposed captured and obsolete equipment to mobilize anti-tank guns, producing the Marder I from captured French Lorraine 37L tractors, the Marder II from the Panzer II chassis, and the Marder III from the Czech Panzer 38(t) chassis. The Sturmgeschütz III, first designed in 1936-1937, pioneered the casemate-style fully enclosed armor that would define almost all late-war German self-propelled artillery. It became the single most-produced armored fighting vehicle Germany built in World War II.

• 5. Soviet and Rocket Paths

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  The Soviet Union took a different path from both the British and the Germans. Rather than developing a specialized indirect-fire vehicle, Soviet designers followed a tradition of dual-purpose towed artillery and built a series of versatile assault guns capable of both direct and indirect fire. The SU-85 was the first of the Samokhodnaya Ustanovka casemate-armored series to appear at the front, arriving in 1943. By late 1944 the SU-100 had arrived, mounting powerful guns on modern chassis in the same fully enclosed casemate configuration the Germans had used with the Sturmgeschütz III.

  The Soviets also pursued a weapon with no real German equivalent: the Katyusha multiple rocket launcher. It was an unarmored truck fitted with a simple rocket rack, cheap to build and devastating in use. It provided area saturation rather than precise fire, making it a different kind of weapon from anything else on the battlefield. The Axis captured examples and produced their own versions; Germany created the 8 cm Raketen-Vielfachwerfer, and Romania developed the Maresal tank destroyer, an early prototype of which was actually armed with a Katyusha. The Soviet ISU-152, a fully casemated assault gun mounting a 152 mm howitzer, paired with the German 105 mm howitzer-armed StuH 42 built on the StuG III, represented the apex of heavily armored direct-fire support vehicles. Both types were designed to deliver powerful high-explosive projectiles against enemy defenses in support of infantry.

• 6. Shoot and Scoot

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  The core tactical advantage of self-propelled artillery over towed guns can be stated simply. Before a towed gun can fire, it must stop, unlimber, and be set up by its crew. Before it can move again, it must be limbered up and towed to the next location. A self-propelled gun can stop, fire almost immediately, and drive away before a counterattack arrives. This shoot-and-scoot capability is especially valuable in mobile conflict and on open battlefields where position is everything.

  Modern self-propelled artillery has extended that advantage further with computers. Current systems can self-survey their firing positions using GPS and inertial navigation systems, coordinate through digital fire control and ballistic computers, and disperse individual guns across a wide area while still delivering rounds on target simultaneously with the rest of a battery. A modern battery of six guns, each firing 43-kilogram projectiles at a burst rate of four rounds per minute, can deliver more than a tonne of ordnance per minute for up to four minutes. The G6-52, the latest version of the 155 mm G6 howitzer, can fire up to six rounds in quick succession that will land nearly simultaneously. It achieves this by firing shells at different trajectories, so the first round has the longest flight time and the last the shortest. That is an improvement on the concept of multiple-round simultaneous impact, itself a development of the earlier time-on-target approach.

• 7. Mortars and Rockets

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  Self-propelled mortar carriers occupy a distinct corner of the category. Vehicles as different as improvised civilian trucks and the M113 armored personnel carrier have carried mortars as primary weapons. The 2S31 Vena is one purpose-built example. The Israeli Makmat mortar carrier is built on the M4 Sherman tank chassis. At the extreme end of the caliber range, the Russian army operates the 2S4 Tyulpan, a self-propelled 240 mm heavy mortar. The Israeli Merkava main battle tank carried a 60 mm mortar in its rear troop compartment, firing through a roof opening so the crew could stay protected; because the mortar was a secondary weapon, the Merkava itself is not classified as a mortar carrier.

  Rockets represent a separate branch of the family with their own logic. Greater range and far fewer restrictions on caliber allow rocket systems to carry much more complex payloads than conventional guns. A multiple launch rocket system can saturate a large area with sub-munitions, filling a role that tube artillery simply cannot. The Finnish-Swedish joint venture Patria Hagglunds manufactures AMOS, the Advanced Mortar System: a 120 mm automatic twin-barrelled, breech-loaded mortar turret. Since the Vietnam War, heavy transport helicopters have also been used for rapid artillery deployment, mitigating one of the traditional advantages of self-propelled over towed guns, though at considerable cost and risk.