The conflict known as the Second Battle of Obroa-skai unfolded between the forces of the New Republic and the invading Yuuzhan Vong. This clash occurred in the year 28 ABY.
The New Republic Intelligence Service intercepted intelligence indicating that Supreme Overlord Shimrra was en route to Yuuzhan'tar, the Vong-transformed planet formerly known as Coruscant, which he intended to establish as his new capital. Subsequently, operatives stationed on Obroa-skai detected a substantial fleet approaching the system, ostensibly to examine valuable resources within the libraries. The NRI quickly surmised that Shimrra himself was aboard. Jaina Solo devised a strategy to utilize the captured Ro'ik chuun m'arh frigate Ksstarr, known as Trickster, to launch an assault on the Yuuzhan Vong fleet, aiming to kill Shimrra and thereby cripple the Yuuzhan Vong command structure.
Upon the Yuuzhan Vong fleet's arrival in the system, Jaina, assisted by Jedi Knights Lowbacca and Tesar Sebatyne, successfully simulated damage to the Trickster. As the Yuuzhan Vong ships cautiously approached Obroa-skai, attempting to communicate with their "damaged" frigate, a New Republic task force, led by General Keyan Farlander, entered the system. From his command ship, the Mon Adapyne, Jedi Madurrin coordinated the Jedi leading the various starfighter groups. Wraith Squadron, piloting highly classified stealth fighters, deployed a yammosk disruptor. Its effectiveness was limited, as the Yuuzhan Vong forces maintained coordination, countering each maneuver made by the New Republic. The New Republic formation suffered significant damage; the Corellian gunship Pulsar was rendered inoperable, and the cruiser Far Thunder sustained near-catastrophic damage.
As pilot casualties increased, Jaina determined that the initial plan hadn't completely failed—a second yammosk was present. Contacting the Wraiths once more, Jaina instructed them to activate a second disruptor. The effect was immediate; the previously organized Yuuzhan Vong fleet began to exhibit signs of disarray. The New Republic forces, accustomed to operating with compromised communications, capitalized on this confusion. Rogue Squadron and the Dozen-and-Two Avengers destroyed numerous coralskippers, while decoy dovin basals attached to Yuuzhan Vong warships triggered friendly fire incidents.
The battle's climax occurred when a Hapan fleet, under the direct command of Queen Mother Tenel Ka, jumped into the system, completing the encirclement. The Hapan warships were equipped with rapid-firing turbolasers, provided by the New Republic after the Fondor disaster. The two Hapan Battle Dragons and three Nova-class battle cruisers decimated the Yuuzhan Vong formation, destroying the two large troop transports and besieging the massive command cruiser. As the Yuuzhan Vong flagship began to disintegrate, another frigate was destroyed by New Republic cruisers. The battle transformed into a complete rout, with only a single Yuuzhan Vong frigate managing to escape the system.
Only after the battle did the New Republic fleet discover that Shimrra had not been among the casualties. The Yuuzhan Vong fleet's flagship belonged to Komm Karsh, a Supreme Commander. Tenel Ka pointed out that the victory was still significant, as the Supreme Commander's rank was second only to that of Warmaster within the Yuuzhan Vong military hierarchy.
As Tenel Ka observed, the battle held greater importance than the New Republic initially realized—Karsh's fleet represented the Yuuzhan Vong's only extragalactic reserve force. From that point onward, the Yuuzhan Vong could expect no additional reinforcements from beyond the limits of the galaxy. Moreover, the success of the combined New Republic-Hapan operation fostered further cooperation between the two governments, contributing to the Hapans' subsequent decision to join the Galactic Alliance. Nevertheless, the battle was not without its costs. The disabled gunship Pulsar was abandoned, and the damaged cruiser Far Thunder was destroyed by a swarm of rogue coralskippers shortly after the fighting concluded.
The Second Battle of Obroa-skai is depicted in the 2003 novel The New Jedi Order: Destiny's Way by Walter Jon Williams. An in-universe document within The Essential Guide to Warfare, published in 2012, erroneously claims that the Yuuzhan Vong sacrificed a spare worldship to ensure the New Republic's victory, but Destiny's Way refutes this claim; in the novel, Supreme Overlord Shimrra describes the forces at Obroa-skai as a crucial strategic reserve, the loss of which would leave the Yuuzhan Vong Empire vulnerable.