- "Symbols are extremely important to the New Republic. That the new government has taken the traditional capital of the Empire, and the Republic before it, is an important symbol of change to the galaxy. The fact that Thrawn could so masterfully manipulate this symbolism to his own advantage underscores the importance of the Siege of Coruscant."
- ―Voren Na'al
The Siege of Coruscant was a major space battle in 9 ABY during the Thrawn campaign. Since his forces were outnumbered by the New Republic defenses of Coruscant, Imperial Grand Admiral Thrawn used cloaking technology to create an effective siege weapon. To do this, he fitted twenty-two asteroids with cloaking devices and placed them on-board several of his Star Destroyers.
- "When we're finally ready to draw the Coruscant sector fleet into ambush, Mrisst will be the perfect lure to use. If they come out to meet us, we'll defeat them then and there. And if they somehow sense the trap and refuse to engage, we'll have our forward base. Either way, the Empire will triumph."
- ―Grand Admiral Thrawn to Captain Pellaeon
Dark Jedi Joruus C'baoth, the clone of Jorus C'baoth, insisted that the Imperial Grand Admiral Thrawn, commander of the Empire at that time, launch a planetary attack on Coruscant to bring the Solo twins to him after Molo Himron's Imperial commando team failed to capture them. This also served Thrawn's purposes, as the Grand Admiral had been planning an attack into the heart of the New Republic. Despite C'baoth's belief that the Grand Admiral wouldn't do as he had commanded, and the fact that C'baoth took control of the Chimaera and its crew, Thrawn agreed to prepare the attack on Coruscant, after replacing the crew on the Chimaera injured by C'baoth's taking control with a five hundred man caretaker crew from Captain Dorja.
Thrawn agreed to prepare the fleet for an attack upon Coruscant once his special cargo of asteroids from Bilbringi had been taken on board the ships of his fleet. Despite having been the one who had insisted upon the attack, C'baoth requested to be taken back to the Mount Tantiss citadel on Wayland while the Imperial fleet was mobilizing to attack Coruscant. The Draklor, under the command of Freja Covell, was detached from the fleet to take C'baoth to Wayland. Shortly after C'baoth left, Thrawn's fleet departed for Coruscant.
Prior to the siege, Grand Admiral Thrawn attacked the planet Mrisst to distract the Coruscant sector fleet away from Coruscant. This strategy left the New Republic capital world defenseless when Thrawn launched the Siege of Coruscant.
The battle began when ten Interdictor cruisers and eight Katana Dreadnaughts dropped out of hyperspace near Coruscant, quickly followed by six Imperial-class Star Destroyers. The Imperial ships were engaged by Coruscant's defense fleet and a pair of Golan III platforms, but New Republic Admiral Hiram Drayson and his navy, including the Home Guard Fleet, were thoroughly outmatched by Grand Admiral Thrawn's tactical skill. Thrawn, who was commanding the Imperials from the bridge of his flagship the Chimaera, assisted by his Captain, Gilad Pellaeon, outmatched Drayson in many tactical areas, giving the Imperials an original advantage. New Republic General Garm Bel Iblis, observing the battle, recognized the Grand Admiral's favored tactic of using Interdictors to aid in precision microjumps during battle. However, he was unable to warn Drayson before two Victory-class Star Destroyers jumped in to ambush one of the Golan platforms at close range. V-150 Planet Defender ion cannons were fired uselessly at Thrawn's ship, although these had as much chance of hitting the Golan III battle platforms as they did Thrawn's fleet. Although DP20 Corellian gunships, X-wings and B-wings were used to engage the Empire, they were unable to stop the plans that Grand Admiral Thrawn was preparing to implement. Shortly afterwards, Bel Iblis took command of Coruscant's forces at the urging of the Head of State of the New Republic, Mon Mothma, as Bel Iblis had previously refused to take command until being approved by Mon Mothma, so as to make sure she trusted him. Bel Iblis pulled back the ships that were defending the Golan platforms, knowing better than Drayson the amount of punishment they could sustain. This effectively gave Thrawn two choices; either he could remain where he was and duel with the battle stations, or he could follow the defenders down to where he would be vulnerable to ground-based weaponry.
At this point, Thrawn ordered the Death's Head and other ships under his command to place asteroids into low orbit in time with the Chimaera, before ordering the retreat into hyperspace, creating an invisible hazard field around the galactic capital. In addition to the twenty-two actual asteroids, Thrawn also staged 265 false launches. As the cloaked asteroids were undetectable to Coruscant's sensors, it was impossible for the New Republic to distinguish an actual asteroid launch from a false one. The first asteroid launched collided with the escort frigate Evanrue. General Bel Iblis, correctly guessing the nature of the cloaked object, ordered the Dreadnaught Harrier to fire at the asteroid's calculated position with its ion cannons. Thrawn allowed the asteroid's cloak to be disabled, revealing that it was indeed an asteroid, before destroying it with turbolaser fire so that it could not be subjected to closer study. Following the successful launch of the cloaked asteroids, the Imperial forces withdrew.
- "For the moment at least, Coruscant is effectively out of the war."
- ―Grand Admiral Thrawn
Though Imperial forces had retreated, the New Republic was now faced with several major problems. They could not drop the energy shield around the planet for fear that an asteroid might hit the heavily populated cityscape nor could they allow space traffic near the planet in case of collisions. Originally, Rieekan and Bel Iblis, amongst others, were able to implement a project in which a dust cloud was released from the first transport, before the Harriers negative ion beams were used to focus it. This dust cloud then would show any asteroids to fly into it, allowing the defenders to destroy it. Although this was effective on the first time, it was later decided to be too time consuming, and so was given up on in favor of acquiring a crystal gravfield trap, a sensor which would detect the cloaked asteroids in orbit around Coruscant. Although Republic ships successfully destroyed all of the asteroids by firing blindly into space, they had no fail-safe way of detecting the asteroids, or of knowing how many asteroids were originally launched and how many remained floating in orbit. As a result, the galactic capital world was effectively blockaded until a method could be devised to detect and eliminate the phantom asteroids.
This series of events led to the Battle of Bilbringi, in which the New Republic attempted to steal a crystal gravfield trap to locate any remaining asteroids in orbit around Coruscant. When Thrawn was assassinated during the battle, the New Republic successfully acquired the gravfield trap and was finally able to lift the quarantine.
- The Last Command (First appearance)
- The Last Command audiobook
- "Shadows of Darkness"—Star Wars Adventure Journal 4 (Mentioned only)
- Before the Storm (Mentioned only)
- Specter of the Past (Mentioned only)
- Specter of the Past unabridged audiobook (Mentioned only)
- The New Jedi Order: The Final Prophecy (Mentioned only)
- Dark Empire Sourcebook
- The Last Command Sourcebook (First identified as Siege of Coruscant)
- The Thrawn Trilogy Sourcebook
- The Essential Chronology
- The New Essential Chronology
- The Essential Guide to Weapons and Technology
- The Essential Atlas
- The Essential Guide to Warfare
- The Essential Reader's Companion