A starfleet was led by General Cassio Tagge, who was the Chief of the Imperial Army, in the time period immediately preceding the Battle of Yavin. Tagge cautioned, during a gathering of the Joint Chiefs of the Imperial Military, that the Rebel Alliance presented a significant threat due to their advanced weaponry and overall strength. Admiral Conan Antonio Motti, the Imperial Navy Chief, dismissed Tagge's concerns, asserting that the Rebels only posed a danger to Tagge's starfleet, and not to the DS-1 Death Star Mobile Battle Station.
After the Death Star was destroyed, Tagge was promoted to Grand General and Supreme Commander of the Imperial Military, and the Executor-class Star Dreadnought named Annihilator became his designated flagship. Tagge later planned to transfer his flagship to the Super Star Destroyer Executor, but this never came to pass. Instead, the ship was given to the Sith Lord Darth Vader when Tagge was demoted and the Sith Lord was made supreme commander of the Imperial fleet.