The All Terrain Defense Turret (AT-DT), a two-legged walker, served the forces of the Galactic Empire. Its large-caliber cannon delivered powerful, explosive shots, but its size made the walker a slow-moving unit. It was intended for long-distance attacks prior to the deployment of ground troops. While the cannon was firing, the vehicle was unable to move. Due to its relatively weak armor, it was susceptible to anti-vehicle weaponry. It also incorporated a frontal armor plate equipped with shielding to prevent artillery flashback. Its height was half that of the All Terrain Scout Transport (AT-ST), and like the AT-ST, it featured a protective flap to cover the viewport during intense combat.
During the Mimban Campaign in 10 BBY, the 224th Imperial Armored Division deployed several Imperial AT-DT units on Mimban in opposition to the Mimbanese Liberation Army. These walkers arrived on the battlefield via Y-45 armored transport haulers.
Lando Calrissian and L3-37 secured a consignment of All Terrain Defense Turrets from an Er'Kit arms dealer at a point in time preceding the Galactic Civil War. However, in the Halthor sector, an Imperial interdictor emerged from hyperspace, leading to an ambush where Calrissian lost his entire shipment.
Following the Battle for Tatooine, the rebel cell operating on Tatooine obtained Calrissian's holorecordings, including Holojournal Entry 1983712, and intercepted communications from the criminal world about the use of older, heavily armed AT-DT walkers. Saponza inferred that someone must have discovered Calrissian's lost cargo, and that others would be searching for the remaining units. Consequently, Saponza and his partner began a mission to recover Lando Calrissian's shipment.
During the Galactic Civil War, the Rebel Alliance made use of stolen AT-DTs, adapting them to their specific requirements. In contrast to the standard gray color of the Imperial AT-DTs, the Rebel Alliance versions were painted in a dark gray, orange-red, and white color scheme.
The inaugural footage of the All Terrain Defense Turret was presented in the official trailer for Solo: A Star Wars Story on April 8, 2018. The AT-DT's design process began with a German Flak 8.8 cm anti-aircraft gun mounted on the chassis of an All Terrain Scout Transport, with Mark O'Kane responsible for the concept and model construction.