Profile view of an AT-DT
In 10 BBY, during the Mimban Campaign, several Imperial AT-DTs were deployed on Mimban by the 224th Imperial Armored Division to fight against the forces of the Mimbanese Liberation Army. They were delivered to the battlefield by Y-45 armored transport haulers.
Sometime prior to the Galactic Civil War, Lando Calrissian and L3-37 met with an Er'Kit arms dealer and acquired a shipment of All Terrain Defense Turrets. Calrissian and L3, however, were ambushed in the Halthor sector when an Imperial interdictor dropped out from hyperspace. As a result of the ambush, Calrissian lost the entire shipment.
After the Battle for Tatooine, the rebel cell based on Tatooine came into possession of Calrissian's holorecordings, including , and received chatter from the criminal underworld of the older and heavily-armed AT-DT walkers being utilized. Saponza deduced that someone must have found Calrissian's shipment, and that people would be hunting for the rest of the cargo. Saponza and his partner embarked on a .
A Rebel AT-DT
During the Galactic Civil War, the Rebel Alliance utilized stolen AT-DTs and re-purposed them to suit their needs. Rather than being standard gray like the AT-DTs used by the Empire, the Rebel Alliance's had a dark gray and orange-red color scheme with a touch of white.
The first footage of the All Terrain Defense Turret was shown in the Solo: A Star Wars Story official trailer on April 8, 2018. The AT-DT design started out as a German Flak 8.8 cm anti-aircraft gun on the body of an All Terrain Scout Transport, with the concept and model built by Mark O'Kane.