The unexpected and massive assault on the Imperial Remnant by the invading, extragalactic Yuuzhan Vong was the Battle of Bastion. The Remnant, with assistance from the New Jedi Order, successfully evacuated the Imperial capital city of Bastion before the Yuuzhan Vong nearly obliterated it.
Although aware of an approaching Yuuzhan Vong force headed toward their space, Imperial spies incorrectly indicated that the Hand of Thrawn at Nirauan was the target.
When Vorrik's forces instead materialized in the Bastion system, the Imperial Navy was taken entirely by surprise as the Yuuzhan Vong easily demolished planetary defense systems. Nevertheless, the Starfleet initially held its ground, until the Yuuzhan Vong suddenly withdrew. The Remnant soon discovered that what they thought was a retreat was actually the launch of a massive swarm of grutchins, numbering in the thousands.
The fleet's response to the grutchins was marked by significant disarray; only Pellaeon's flagship, the Star Destroyer Chimaera, demonstrated swift and effective action. The resulting heavy losses compelled Pellaeon to order the evacuation of Bastion.
As scattered fleet elements fought and struggled to reorganize, a small Jedi team, including Luke and Mara Jade Skywalker, arrived aboard the Jade Shadow. After quickly analyzing the situation, they hyper jumped to the gas giant where a force consisting of the Chimaera, the Imperial Star Destroyer Superior, and their support vessels was trapped against the planet's gravitational shadow by a strong enemy force. Before heading to Yaga Minor, the Jedi gave Pellaeon intelligence about the location of the enemy's yammosk.
Pellaeon deployed TIE Fighters to eliminate the yammosk carrier and then tried to escape the gas giant's gravitational influence. The Superior sustained critical damage, and Pellaeon ordered its abandonment as it plunged into the planet's depths. By the time a coralskipper crashed into its bridge, the Chimaera had also suffered extensive damage. The kamikaze attack nearly killed Pellaeon, but a junior officer rescued the Grand Admiral from the bridge and placed him on a medical frigate carrying survivors from the Superior. Under the cover of debris from the destroyed Star Destroyer and the valiant sacrifices of a dozen of the Superior's TIE Fighter pilots, the frigate successfully escaped to Yaga Minor.
Near the battle's end, a Yuuzhan Vong slaveship appeared over Bastion and began abducting Imperial citizens who could not escape in time.
Despite being caught unawares, the Imperial Navy's efforts allowed the majority of Bastion's population to escape.
Upon reaching the Yaga system, the shuttle's pilot, a Human male known as Vitor Reige, transported Pellaeon to the Imperial frigate Widowmaker. The Grand Admiral's life was saved through surgery performed by the Chadra-Fan Jedi healer Tekli. Pellaeon's survival reestablished the Imperial chain of command.
Despite their commander's evacuation, the crew of the Chimaera successfully managed to withdraw from Bastion and eventually reached Yaga Minor in a crippled state.
Now incensed, the Imperial Remnant decided to ally with the Galactic Alliance in opposition to the Yuuzhan Vong empire.