The largest ground vehicle designed by the Empire, the HA-AT represented the ultimate evolution of Imperial walker design, being considerably larger and more destructive than the Armoured Assault Transport. The Heavy Armoured Assault Transport was first utilised by the Empire during the Battle of Harborage in 20 NE, and while they were successful in annihilating a considerable portion of the New Republic Remnant, they were destroyed by the Aldárae dragon Du'utahrovin. Nevertheless, they were subsequently deployed in critical battlefields across the galaxy in preparation for an invasion by the resurgent New Republic.
As few were created prior to the fall of Orbispira, the Heavy Armoured Assault Transport became valuable commodities to the various Imperial Remnants, with most falling into the hands of the New Empire.
First conceived during the Cyrannian Cold War, the Heavy Armoured Assault Transport was designed with the shortcomings of the Armoured Assault Transport in mind, eliminating many of the weaknesses of the design which became evident in confrontations with the Cyrannian Imperial State during the New Cyrandia Wars. The outbreak of the Second Great Cyrannus War in 15 NE delayed the active production of the HA-AT, which entered service in 20 NE, first seeing use during the pivotal Battle of Harborage, during which Grand Admiral Tector Decimius personally commanded the invasion force from his own personal walker. While the walkers proved deadly in combat, they were all ultimately destroyed by the unexpected attack of Du'utahrovin, who annihilated the entire invasion force.
HA-ATs were later deployed during the Great Battle of Orbispira later that year, though once again fell victim to Du'utahrovin's attack. With the subsequent collapse of the Empire into various Imperial remnants, all remaining HA-ATs fell into the possession of Grand Admiral Henera Medé's faction, which later formed the bedrock for her New Empire.
Representing the ultimate evolution of Imperial walker design, the Heavy Armoured Assault Transport measures fifty metres in length and forty six metres in height, towering over its predecessor, the Armoured Assault Transport. Sheathed in state-of-the-art heavy armour and equipped with heavy and medium laser cannons and a devastatingly powerful FOx1 heavy turbolaser cannon,, the HA-AT is a brutally effective symbol of psychological warfare and a potent symbol of the Empire's might.
Though designed to reduce enemies to abject terror, the first two deployments of the HA-AT, namely the Battle of Harborage and the Great Battle of Orbispira demonstrated the walker's weakness to the unexpected, with both engagements ending in their destruction by Du'utahrovin. Nevertheless, both battles proved the effectiveness of the HA-AT in conventional engagements, particularly in siege engagements.
- The Heavy Armoured Assault Transport is based on the AT-M6 from Star Wars: The Last Jedi.