Self-Propelled Heavy Artillery

The Self-Propelled Heavy Artillery (SPHA) walker was a modular artillery unit used by the Grand Army of the Republic during the Clone Wars.

Developed by Rothana Heavy Engineering, a covert subsidiary of Kuat Drive Yards, the SPHA walker was designed to fulfill the role of mobile ground-based long-range artillery support. In development of the system, engineers on Rothana essentially had to build their prototype around the requirements of the primary weapon: a large, dorsally-mounted external weapon assembly, a powerful reactor core to fulfill the weapon's high energy requirements, and all of the necessary support equipment and crew stations. In order to save weight, designers rejected a complex turreting mechanism, instead relying on the entire walker to reposition in order to adjust for different firing coordinates. Like other walkers, the use of articulated legs prevented the SPHA from being vulnerable to anti-repulsorlift weapons, at the cost of some mobility.

The result of this development process was a walker that possessed a very capable capital ship-class weapon, but was hampered by its low mobility and lack of heavy armor. The powerful reactor core used to provide power to the main weapon was susceptible to meltdowns when under enemy fire, causing tremendous collateral damage. As such, SPHA units were used primarily in safe firebases, far behind friendly lines and guarded heavily.

The SPHA walker chassis served as the basis for a number of different weapons platforms, though the best chronicled version was the SPHA-T (turbolaser) configuration. This variant's main weapon was a heavy turbolaser cannon, capable of causing extreme direct fire damage to large or slow-moving targets. The primary disadvantage of this powerful weapon was that it was incapable of providing indirect fire support to out of sight locations, a problem remedied in other models.



Some of these other variants deployed during the Clone Wars include the ion cannon (SPHA-I), anti-vehicle laser (SPHA-V), concussion missile (SPHA-C), and mass-driver models. Some of these model variations included 12 retractable antipersonnel blasters, necessitating an additional 10 gunners to the command crew of 15.

Unlike smaller walkers, such as the AT-TE, SPHA units were unable to be carried into battle by LAAT/c gunships because of their large size and weight. Instead, they were deployed directly from landed Acclamator-class assault ships, which could carry 36 of the artillery platforms.

The SPHA-T first appeared in the Battle of Geonosis where it was instrumental in shooting down several Lucrehulk-class core ships and Hardcell-class interstellar transports. At the suggestion of Anakin Skywalker, many Venator-class Star Destroyers of the Open Circle Fleet had SPHA-T turbolaser cannons installed inside their ventral hanger bays, where they were used effectively during the Second Battle of Coruscant.

The SPHA-line walkers would still see service in the early years of the Galactic Empire, until the Self Propelled Medium Artillery-line was developed. Being equipped with weapons-generators equally powerful to the ones installed in the old SPHA walkers, it's reasonable to believe that the SPHA-chassis would in turn recieve similar new developments as upgrades to retain its title of "Heavy Artillery". The variants equipped with projectile ordnance would also have no need for replacements, since the amount of ammunition they could carry would always exceed a smaller design.

With their intimidating size fitting the Imperial doctrine of Rule by Fear, it is highly probable that some or all variants of the SPHA were still being used during the Galactic Civil War.

Appearances

 * Star Wars Episode II: Attack of the Clones
 * Star Wars: Clone Wars
 * Chapter 1
 * Chapter 4
 * Chapter 20
 * Star Wars Episode III: Revenge of the Sith
 * A SPHA-T cannon was seen firing on a Munificent-class star frigate from inside a Venator-class Star Destroyer.