The AT-DP Arc Cannon Prototype represented a preliminary version of an Imperial walker. Central to its design was "the Duchess," an arc generator conceptualized by Sabine Wren during her time as an Imperial Academy cadet on Mandalore. This prototype was named in remembrance of the late Duchess Satine Kryze, the former leader of the New Mandalorians during the era of the Clone Wars.
This AT-DP Arc Cannon Prototype was built upon the framework of the All Terrain Defense Pod, and was also known by the moniker "the Duchess." The Duchess was capable of generating an energy pulse. This pulse could target and intensely heat a specific material, with the selection of material being dependent on the configured settings. Initially, it was engineered to specifically target the beskar alloy present in Mandalorian armors. Theoretically, at maximum power and range, it could obliterate entire armies simultaneously. The walker was easily identifiable due to its distinctive white and red color scheme.
[Sabine Wren](/article/sabine_wren]'s initial perspective on the Duchess was that it was merely a test of her abilities. She did not anticipate that the Galactic Empire would actually deploy it, especially not against her own people. However, when testing commenced, Wren experienced regret and took action by sabotaging the prototype and erasing the design plans, subsequently fleeing from the Academy.
Years later, Tiber Saxon, the Imperial governor of Mandalore, revived the project. He used the reconstructed Duchess against Clan Wren when Sabine, along with her new allies from the Rebel Alliance, arrived on Mandalore to free her father, Alrich Wren. After the Mandalorian warriors were reduced to dust, the rebels and their Mandalorian allies, including Lady Bo-Katan Kryze, decided to infiltrate Tiber Saxon's Star Destroyer with the goal of destroying the prototype and its schematics once and for all. However, Wren and Kryze were caught in a trap. Upon reaching the seemingly unguarded arc generator, they were struck by a non-lethal energy burst. Saxon then appeared, offering to spare both of their lives if Wren would agree to enhance the weapon to its full operational capacity.
Feigning compliance, the former Imperial cadet adjusted the generator's settings to target plastoid alloy instead of beskar. Consequently, the energy pulse affected all of the Imperial stormtroopers and Governor Saxon, who were wearing armor made of plastoid, immobilizing them. Wren briefly considered retaining the Duchess for use in the Alliance's fight against the Empire, as she watched her enemies struggle in pain. However, Kryze brought her back to her senses, and Wren destroyed the device permanently by using the Darksaber to slash its power core. Simultaneously, elsewhere on the Star Destroyer, her Jedi friends Kanan Jarrus and Ezra Bridger, together with the astromech droid Chopper, succeeded in deleting all data related to the machine. Shortly after, the Duchess overloaded and exploded, resulting in the destruction of the AT-DP Arc Cannon Prototype, Saxon, and the entire ship, thus preventing the Empire from recreating the weapon.