In Heir to the Empire (1991), master tactician Grand Admiral Thrawn plots to destroy the New Republic despite their numerical advantage over the remaining Imperial forces. He sets his sights on the Wayland storehouse of the late Emperor Palpatine, which contains a massive array of Spaarti cloning cylinders and a working cloaking shield. To this end, Thrawn and his subordinate Gilad Pellaeon, captain of the Star Destroyer "Chimaera", enlist the help of smuggler Talon Karrde and his second-in-command Mara Jade to obtain several salamander-like creatures called ysalamiri. Thrawn uses the ysalamiri, which possess the natural ability to disrupt the Force, to subdue the storehouse's guardian Joruus C'baoth, a twisted clone of a Jedi Master whom the Grand Admiral had killed years before. C'baoth offers his allegiance in exchange for two acolytes to bend to his will: Darth Vader's twin children, Luke and Leia. Thrawn sends some of his Noghri killers to capture Luke and a pregnant Leia, but their attempts repeatedly fail. Leia defends herself from one attack and is surprised when the Noghri suddenly surrenders. Thrawn launches his first offensive, a series of hit-and-run attacks into New Republic territory, and then steals a complement of mole miners from Lando Calrissian's mining operations on Nkllon. In need of warships, and with his previous tactics having forced over 100 lightly manned ships to be stationed at the Sluis Van shipyards as he planned, Thrawn invades. His stormtroopers use the stolen miners to board and hijack the ships, but they are thwarted when Lando can seize control of the miners remotely. The Grand Admiral withdraws his forces, but thanks to Thrawn's plotting, his New Republic nemesis Admiral Ackbar is soon arrested for treason.