Death Star
The first Death Star is depicted in various sources of having a crew of 265,675, as well as 52,276 gunners, 607,360 troops, 30,984 stormtroopers, 42,782 ship support staff, and 180,216 pilots and support crew. Its hangars contain assault shuttles, blastboats, Strike cruisers, land vehicles, support ships, and 7,293 TIE fighters. It is also protected by 10,000 turbolaser batteries, 2,600 ion cannons, and at least 768 tractor beam projectors. Various sources state the first Death Star has a diameter of between 140 and 160 kilometers. There is a broader range of figures for the second Death Star's diameter, ranging from 160 to 900 kilometers.
Rebel Alliance
During the events of "Rogue One" and "A New Hope", the Alliance learns of the construction of the "Death Star", an enormous battle station intended to secure the Empire's power. With the help of the "Rogue One" squad led by Jyn Erso and Cassian Andor, the Rebels successfully steal the schematics of the station. This win was the Alliance's first major battle against the Empire on Scarif; but at a 75% casualty rate and with all remaining imperial and rebel forces planetside decimated. After successfully downloading the Death Star plans, Alderaanian soldiers aboard a Mon Calamari flagship barely manage to escape Imperial forces with the stolen data plans. Right after the battle, the "Tantive IV", an Alderaanian corvette carrying Princess Leia Organa is captured by the Imperial fleet while attempting to deliver the Death Star Plans to Bail Organa on Alderaan. All members of the Alderaanian Consular Security onboard are either killed or taken prisoner and Princess Leia Organa is held hostage for a time by Darth Vader. In order to punish both her and her home planet's central involvement in the Rebel Alliance, Leia is forced to witness Alderaan's destruction by the Death Star. The Princess is subsequently rescued by Luke Skywalker, Han Solo, Chewbacca, and Obi-Wan Kenobi, who then deliver the station schematics to the Alliance. This leads directly to the Alliance's victory in the Battle of Yavin and the loyalty of Luke Skywalker; the Rebellion's only remaining member with training in the Force.