Unstable Terrain Artillery Transport The Unstable Terrain Artillery Transport ( UT - AT ) , also known as the " Trident , " was a military transport and assault vehicle that served the Grand Army of the Republic during the Clone Wars when the use of walkers was unsuitable . Slow and vulnerable , the vehicle was adept at crossing bridges and traversing unstable terrain , but due to its elevated position it was constantly prone to enemy attack . Alternate configurations of the UT - AT were stocked with bridge laying equipment , converting the transport into an effective trail blazer . The vehicle was developed by Kuat Drive Yards and Mekuun Corporation following a disastrous use of walkers on the agriworld of Agamar . Realizing that walkers were not the answer in such situations , the two companies developed a repulsorlift ski system , which involved a series of undulating panels that would adapt to different terrain . The vehicle was favored by Jedi General Ki - Adi - Mundi , and was used to great effect on Mygeeto and Cato Neimoidia . Description . Since the heavy footfalls of Republic walkers had caused bridge collapses on the front lines , Kuat Drive Yards and Mekuun Corporation eliminated the catalyst altogether . Instead of " legs , " the UT - AT featured 16 low - power repulsorlift skis that would shift to properly balance the vehicle depending on the terrain . Four additional repulsorlift plates were located under the main carriage for propulsion . The skis also had the ability to reverse their repulsion , causing gription fields and allowing the vehicle to ascend sheer surfaces if needed . The skis supplied superior stability when firing , and were particularly effective on unstable terrain . Although the skis canceled out the weight of the vehicle , it was still difficult to maneuver due to its significant inertial mass . This limited the recommended speed of the craft to 45 kilometers per hour . The skis were blast - proof , which made them invulnerable to light blaster fire , but not to explosive charges . A significant amount of heat was generated by the undulating plates , which was compensated for by an air vent located towards the front of the vehicle . For armament , the UT - AT had three forward - facing cannons : one dorsal anti - infantry cannon , and two side - mounted medium cannons . This configuration earned it the nickname " Trident . " Bomblet generator s were also installed , allowing drivers to unleash a maelstrom of ion - charged destruction on opposing droid armies . Shells and other artillery were stored externally on racks . Standard configuration UT - ATs also featured four anti - personnel turrets in the rear of the craft , although variants featured supplies to bolster the vehicle ' s standard bomblet generators , while others stored temporary bridge equipment and kits . This configuration would allow UT - ATs to forge a path over unsteady terrain while placing a suitable track for the heavier walkers . The cockpit of the UT - AT had positions for a driver and a gunner , who would operate the two side cannons . Twenty additional troops could be transported in the front half of the vehicle , where the bulk of the internal machinery was also held . Scanning equipment was located under the cockpit , providing the driver with ample data relevant to their field of view . The rear was padded with heavy armor and stations for the anti - personnel gunners , although this would change with alternate variants . History . Origin and development . Despite the fact that the Rothana Heavy Engineering / Kuat Drive Yards All Terrain Tactical Enforcer had served the Grand Army of the Republic well on the battlefield , it did have several drawbacks and pitfalls , as experienced on the planet Agamar during the Mirgoshir campaign . Grand Army walkers attempted to traverse the natural bridges of the planet , but their heavy tread and gross weight prompted their collapse , resulting in the loss of significant amounts of personnel and armor . Kuat Drive Yards saw that their coverage of " All Terrain " had a clear deficiency , and so began devising a new vehicle that could cross bridges with a minimum of fuss , or , at least , would not be the cause of any unfortunate collapses . In an unusual move for the company , Kuat Drive Yards co - developed their new product with Mekuun Corporation , a company known for their expertise with repulsorlift technology , particularly on heavy vehicles . The product of their combined effort was the Unstable Terrain Artillery Transport , a vehicle that was not so much a walker as it was a tank . Application . UT - ATs were put to use in environments not suited to the AT - TE , such as snowy wastelands or shifting surfaces . However , although Kuat Drive Yards and Mekuun had solved the problem of the collapsing bridges , the UT - AT was exceptionally slow and had considerable vulnerabilities . Due to the vehicle ' s elevated position , a significant gap existed between the vehicle and the surface , which could be exploited by well - placed explosives . If hit in such a fashion , the UT - AT would rocket up into the air before crashing back down , usually killing all crew and passengers . The UT - AT was used frequently in the closing stages of the Clone Wars , particularly on worlds with an abundance of bridges , such as Cato Neimoidia and Mygeeto . In the battle for the latter , Jedi General Ki - Adi - Mundi and Commander CC - 1138 utilized several of the vehicles to press the attack . Since Mygeetan cities were interlinked by a honeycomb of bridges , use of the vehicle was pivotal , although many UT - ATs fell prey to the precise shots of Tri - droids . The attack pressed on , however , and CC - 1138 utilized the vehicle ' s bomblet generator to great effect , clearing the way for the troops of the 21st Nova Corps . Behind the scenes . First appearing in George Lucas ' , the UT - AT was named and elaborated on by Billy Buehler and " The Dark Moose " through the StarWars . com feature , " What ' s The Story ? " . Buehler supplied the name and the majority of the information included in the final entry , while " The Dark Moose " contributed technical elements and the final paragraph . " The Dark Moose " had originally called the craft an " All - Terrain Combat Sled , " but this was passed over in favor of Buehler ' s submission . The " What ' s the Story ? " information has gone on to be referenced in three other works of " Star Wars " media : " " , " Guide to the Grand Army of the Republic " , and " The Complete Star Wars Encyclopedia " .