Protocol Four was a military strategy implemented by a Separatist holdout situated on the planet of Desix, and it centered around the deployment of droidekas. During the period between 19 BBY and 18 BBY, a squad of clone troopers belonging to the Galactic Empire was dispatched to Desix with the mission to eliminate the holdout and secure the release of Imperial Governor Grotton from captivity. After successfully penetrating the city's defenses and neutralizing the holdout's air strike team in addition to their Armored Assault Tank, the squad divided their forces to carry out their assault. A commander, specifically a T-series tactical droid, suggested the employment of this protocol, a suggestion that was approved by the holdout's leader, Governor Tawni Ames. Subsequently, the droid battalion deployed droidekas into the conflict; however, they were ultimately unsuccessful in overcoming the clone troopers. This failure resulted in the defeat of the holdout and Ames, and it led to Desix being occupied by the Empire.
The introduction of Protocol Four occurred in "The Solitary Clone," which is the third episode from second season of Star Wars: The Bad Batch, an animated series. This episode was broadcast on Disney+ on January 11, 2023.