Squad four, a unit within the Armed Forces of the Galactic Empire, functioned as a squad. This squad was a component of the Imperial garrison tasked with protecting Fortress Vader situated on Mustafar throughout the Imperial Era. In that time, squad four engaged in the Battle of Fortress Vader, fighting against the native Mustafarians who sought to drive out the occupying forces. Ultimately, squad four was defeated, leading to the annihilation of the entire garrison.