The Death Star Uprising, a significant prison riot, began within Detention Block 2180 located on the first Death Star. In this event, Rebel Alliance prisoners of war attempted a daring escape. They fought their way toward two separate hangars with the intention of commandeering a Sentinel-class landing craft. Although the prisoners were ultimately unsuccessful in their escape attempt, their riotous actions may have served as a distraction for a more crucial and ultimately successful objective. During the chaos of the uprising, a portion of the Death Star plans were covertly stolen and transmitted to Rebel forces stationed at a secret base on Polis Massa.
As construction of the Death Star neared completion, captured enemies of the Empire from across the galaxy were secretly transported to the highly classified space station for interrogation and imprisonment. Within Block 2180, a number of Rebel captives encountered an unidentified Human Jedi prisoner. This Jedi had conceived a straightforward plan for escaping the Imperial battle station, a plan that relied on the cooperation of his fellow inmates.
It's likely that Imperial forces remained unaware of the clandestine prison break until after the rioters had successfully raided an Imperial armory. There, they armed themselves in anticipation of the inevitable stormtrooper counterattacks.
The first stormtroopers to become aware of the disturbance were those stationed in Hangar 84G. These troopers were soon joined by the elite troopers of the 501st Legion, who happened to be on the Death Star for an exterior inspection. Together, they assembled in the hangar and forced the Rebels back through the blast doors they had initially breached. Many prisoners were killed in the ensuing bloodshed, as their recapture proved impossible without a fight. After a brief but intense assault, Hangar 84G was secured and locked down by Imperial forces. The Rebels then shifted their focus toward the Fire Control Room, the location of the superlaser.
Simultaneously, stormtroopers hurried along walkways toward the superlaser, engaging a Rebel who had managed to steal the Death Star's schematics. Unfortunately for the Empire, the bridge that typically spanned a reactor tunnel, connecting Hangar 84G to the Fire Control Room, had been disabled earlier. This forced the stormtroopers to take a longer, alternate route through the prison area. Meanwhile, another group of Rebels successfully reached Hangar 85G, located just beyond the Fire Control Room. They managed to seize control of the hangar long enough to transmit a separate, partial set of the schematics to a Rebel base on Polis Massa. Additional sets of the schematics would later be acquired at Danuta and Toprawa.
All the rioters within the Fire Control Room were eliminated, and Imperial troopers advanced toward Hangar 85G, aiming to prevent the Rebels from fully boarding and hijacking a Sentinel-class landing craft for their escape. With mere moments remaining before takeoff, stormtroopers stormed into the hangar, eliminating as many escapees as possible. The Jedi leader finally revealed himself in a desperate dash toward the shuttle, but Imperial shock troopers detonated it a moment later.
The enraged Jedi activated his lightsabers and cut down any trooper who dared to stand in his path. Ultimately, the Jedi and his remaining squad of troopers were overwhelmed and killed. Imperial intelligence subsequently traced the missing schematics and the few Rebels who managed to escape to Polis Massa, where an even more fiery skirmish would eventually erupt.
The prison break proved to be a significant embarrassment for Darth Vader's supposedly "Elite" 501st Legion, and consequently, for Vader himself. As a form of punishment, Vader reassigned the Legion from their relatively "comfortable" position on the Death Star to his personal army. Their new mission was to assist in the galaxy-wide search for both the stolen Death Star plans and the escaped Rebel prisoners. However, the search proved unsuccessful, and the plans were not recovered in time to prevent the destruction of the Death Star. Despite this failure, the punishment ensured that the Legion was not stationed on the Death Star when it met its end. The troopers who replaced them, however, were ultimately doomed.