While stationed aboard the Death Star, Tagge was placed in charge of army operations as Chief of the Imperial Army.
During a meeting of high-ranking imperial officials aboard the Death Star, Tagge suggested that the Rebel Alliance, whom had stolen plans to the Death Star, were a threat to the Empire and to the Death Star, prompting an argument with Admiral Conan Antonio Motti, who did not believe the rebels posed a threat to the Empire's rule. Tagge then noted that the Rebels had been building support within the Imperial Senate, but their conversation was interrupted by the arrival of Grand Moff Tarkin and Darth Vader, who announced that the Senate had been disbanded by the Emperor.
Shocked by this news, Tagge questioned how the Empire would maintain its control, but Tarkin revealed that regional governors like himself had been given full autocratic power over their territories, also stating that the threat of the Death Star would keep systems in line through fear. Tagge then stated again that the Rebel Alliance was still a threat to that plan due to their possession of the Death Star blueprints, only to be rebuffed by Darth Vader, who claimed that the plans would soon be recovered. and Motti then stated that even with the plans, any attack would be useless against the Death Star. He then sparked an argument between himself and Vader after criticizing the Sith's devotion to the Force. Tagge then watched uncomfortably as Vader force-choked Motti with the Force until Tarkin ordered him to stop. The Grand Moff then informed Tagge that Vader was close to finding the location of both the plans and the hidden Rebel base, noting that once they found it the Rebellion would be swiftly crushed along with any threat it presented to the Empire.
Tagge later left the Death Star to investigate Princess Leia Organa's false claims about an active Rebel base on Dantooine, inadvertently leading to him surviving the destruction of the battlestation at the Battle of Yavin.