The Mark IV assault droid was originally created by the Galactic Republic in the days prior to the Mandalorian Wars, but later became one of the most common droids in the Sith Empire. While the Republic used them as automated defenses, patrolling cities or military installations, the Sith Empire used these droids to fill out their military ranks and also as defense forces on starships throughout the fleet and military bases, like those on Taris and Manaan. These droids were used primarily in a defensive manner, and despite their simple programming, proved exceptionally capable of repelling Republic boarding parties attempting to seize Sith starships. During actual assaults, the Sith preferred to rely upon more mobile forces, such as Sith troopers.
Some of these droids were provided with a bubble-like energy shield which rendered them especially effective against ranged weapons and lightsabers. They were also used by the Ahto City Civil Authority.