Dark Force Rising (1992) reveals that before the Clone Wars, the Old Republic had constructed a fleet of highly automated heavy cruisers, known as the "Katana" fleet. A virus infected the crews of the entire fleet and drove them insane. The fleet was never seen again until smuggler Talon Karrde discovered it (several years before the events of the first book). With access to Palpatine's private storehouse on the planet Wayland, Thrawn presses his advantage to marshal more forces for the battle against the New Republic. Mara Jade, in an attempt to exonerate the Empire's warrant for Karrde's arrest, goes to Thrawn and offers to reveal the location of the "Katana" fleet. Instead, he has her followed and Karrde is captured. Mara and Luke rescue Karrde from Thrawn's Star Destroyer as Thrawn attempts to capture another man who knows about the "Katana" fleet. Meanwhile, Leia learns that the Noghri serve the Empire because they revere her late father, the insidious Vader, who they believe saved their planet Honoghr from ecological disaster. Leia convinces them that they have been deceived and effectively enslaved by the Empire, and they switch sides. With Ackbar temporarily neutralized as a tactical opponent, Thrawn leads an army of clones to claim the so-called ""Katana" fleet", outmaneuvering Luke, Lando, and Han Solo.