The Self-Propelled Heavy Artillery (SPHA), which is also referred to as the Self-Propelled Heavy Artillery Turbolaser (SPHA-T) when it has a turbolaser emplacement, was a customizable gun platform with a dozen legs. Rothana Heavy Engineering was the manufacturer. Within the Clone Wars, they stood as the Grand Army of the Republic's most massive ground-based weapons. During the Imperial Era, the Galactic Empire's Imperial Artillery Corps made use of SPHA-Ts.
The Self-Propelled Heavy Artillery Turbolaser (SPHA-T), alternatively known as the Self-Propelled Heavy Artillery (SPHA), combined the immense destructive power of a built-in laser cannon emplacement with the capacity to advance into combat on strong, jointed legs. Measuring 140.2 meters in length, they were the most substantial ground-based weapons available to the Grand Army of the Republic. The twelve legs were only used when moving between firing locations. When engaging an enemy, the SPHA-T would remain stationary, providing its gunners with enhanced precision for aiming its extremely powerful turbolaser beam. Despite requiring a crew of at least 30 specialized clone troopers for each platform, their power and effectiveness allowed them to penetrate starship shields and hulls. However, SPHA-Ts had a limit to their charging capacity.
SPHA-Ts had the capability to defend landing assault ships and provide destructive direct firepower. These artillery walkers were generally organized in squadrons of four, typically positioned behind advancing walkers like the All Terrain Tactical Enforcer. Onboard Acclamator-class transgalactic military assault ships, SPHA-Ts were stored behind All Terrain Tactical Enforcer walkers, which occupied the front of the bays. During the Clone Wars, thanks to Jedi General Anakin Skywalker, some Venator-class Star Destroyer had extra Self-Propelled Heavy Artillery cannons at their ventral docking bay. These laser cannons enhanced ventral firepower.
Rothana Heavy Engineering produced 100 SPHA-Ts, which were strategically positioned on various battlefronts during the First Battle of Geonosis, the opening conflict of the Clone Wars. They were deployed in groups of four behind advancing All Terrain Tactical Enforcers, with Low Altitude Assault Transport/carriers providing defense with AT-TEs and infantry on foot. These forces mobilized around and in front of the SPHA-Ts, extending several kilometers. The SPHA-Ts coordinated with infantry and AT-TEs to establish a strong defense line for the fleet of Acclamator-class transgalactic military assault ships. These ships landed just outside the Petranaki Arena, serving as an assembly point for the formidable juggernauts.
During the battle, they demonstrated exceptional effectiveness on the battlefield under the command of Jedi Master Yoda. Master Yoda ordered one squadron to concentrate fire on a retreating core ship. This action caused antigrav repulsorlift malfunctions, creating a tractor beam effect with the ground. This greatly accelerated its fall and resulting in the ship's destruction. Following these shots, the SPHA-Ts required replacement with charged guns from the rear lines.
During the Battle of Coruscant, a SPHA-T situated in the hangar of a Venator-class Star Destroyer engaged a Munificent-class star frigate, eliminating the enemy ship as Skywalker and Obi-Wan Kenobi passed by. After the Clone Wars and the rise of the Galactic Empire, the Imperial Army's Imperial Artillery Corps utilized SPHA-Ts as mobile artillery. Eventually, the smaller and faster SPMAs replaced the SPHA-Ts.
The Self-Propelled Heavy Artillery, initially conceived for the 2002 film Star Wars: Episode II Attack of the Clones, was designed through concept sketches by Concept Design Supervisor Erik Tiemens. His initial concepts featured the self-propelled cannon mounted on treads. However, George Lucas suggested a walker design, similar to its AT-TE counterpart. During production, the SPHA-T was referred to as "Clone Tank A." An early animatic depicted SPHA-Ts deploying from Acclamator-class assault ships on Geonosis, but this scene was removed from the final film.
The RX-200 Falchion-class assault tank featured in "The Zillo Beast" and "The Zillo Beast Strikes Back" was redesigned from the SPHA-T to more closely resemble the maser tanks from the Godzilla franchise.
The databank size of 140.2 meters doesn't align visually with the physical appearances in Attack of the Clones, from which the Legends size of "Less than 60 meters" originates. The CGI model used in the film appears slightly larger than twice the length of an AT-TE, rather than significantly larger as the databank suggests. The 2018 canon reference book, Star Wars Encyclopedia of Starfighters and Other Vehicles by Landry Q. Walker, also states a length of 140.2 meters.