Harbinger, a heavily-armed Mon Calamari Star Cruiser, functioned as the flagship for General Garm Bel Iblis during the latter stages of the Yuuzhan Vong War. Initially, it protected the planet Tallaan from Yuuzhan Vong assaults. Later, the Harbinger took part in the New Republic's rout of Yuuzhan Vong forces within the Treskov system in 28 ABY. Subsequently, this Star Cruiser assisted the New Republic's successor, the Galactic Alliance, in the defense of the planet Mon Calamari against a Yuuzhan Vong armada in 29 ABY. The Harbinger and the Galactic Alliance forces engaged this armada at the edge of the Mon Calamari system, where the Star Cruiser effectively utilized its powerful armaments. After this battle, Bel Iblis and the Harbinger joined elements of the Galactic Alliance fleet in the liberation of the planet Corulag from Yuuzhan Vong occupation.
The Harbinger, a Mon Calamari Star Cruiser, boasted heavy armament, including long-range weaponry. It was outfitted with a command bridge, engines, a hyperdrive system, and life support capabilities.
During the Yuuzhan Vong War in 28 ABY, when the extra-galactic Yuuzhan Vong invaded the galaxy, the Harbinger functioned as the flagship for fleet units commanded by General Garm Bel Iblis, who was allied with the New Republic. Its initial mission was to safeguard the planet Tallaan from the invading forces. Responding to a summons from Jedi Master Luke Skywalker, Bel Iblis took half the fleet from Talaan, including the Harbinger, to assist the New Republic in setting a trap for the Yuuzhan Vong within the Deep Core's Treskov system, close to the moon Ebaq 9. Once the Yuuzhan Vong fleet was drawn into the system, Skywalker, operating from the Harbinger's bridge, directed the ships of Bel Iblis's force, along with a contingent from the Smugglers' Alliance coalition, to engage the Yuuzhan Vong's Battle Group of Yun-Q'aah as part of the Battle of Ebaq. The New Republic forces achieved victory in this battle, during which Warmaster Tsavong Lah of the Yuuzhan Vong was killed. Supreme Commander Sien Sovv of the New Republic delivered his report from the Harbinger after the battle's conclusion.
Later, the Harbinger was among the many warships assembled near the planet Mon Calamari to support the Galactic Alliance, the successor to the New Republic, in its defense of the ocean planet from a large Yuuzhan Vong armada in 29 ABY. The Harbinger and Galactic Alliance forces encountered the approaching armada at the edge of the Mon Calamari system. The enemy formation resembled a yammosk, a tentacled creature possessing telepathic abilities. After Galactic Alliance starfighters created openings in the armada's arms, which were composed of lighter Yuuzhan Vong ships, the Harbinger and the Super Star Destroyer Guardian unleashed their long-range weapons on the Yuuzhan Vong capital ships at the armada's core through these newly created firing lanes. As the battle progressed, the Yuuzhan Vong armada deployed the shielding effects of its dovin basals to protect itself from the Harbinger, the Guardian, and the Viscount-class Star Defender Viscount, thus mitigating the impact of the trio's battleships.
To divert the dovin basals' focus, Galactic Alliance bombers infiltrated the armada, forcing the Yuuzhan Vong to defend against a new threat. This shift in defenses allowed the Harbinger and Guardian to freely target the poorly defended arms of the armada, destroying numerous coralskippers and picket ships. Shortly thereafter, the Yuuzhan Vong armada retreated from the battle. Following the engagement in the Mon Calamari system, Bel Iblis and the Harbinger joined a battle group comprising the Imperial-class Star Destroyers Mon Mothma and Elegos A'Kla, along with the MC80B Star Cruiser Mon Adapyne, to conduct a surprise attack and liberate the Yuuzhan Vong-held world of Corulag. The Harbinger, traveling with the battle group from the planet Contruum, exited hyperspace near Corulag after the other three Galactic Alliance warships and rendezvoused with the Elegos A'Kla.
Aided by the other capital ships, the Harbinger trapped the Yuuzhan Vong vessels, and the resulting crossfire eliminated many enemy coralskippers. During the conflict, Peace Brigade TIE fighters, aligned with the Yuuzhan Vong, launched from Corulag. General Tycho Celchu, commanding the Elegos A'kla, was tasked with addressing this threat, with the Harbinger prepared to assist if needed. Ultimately, Corulag was freed from Yuuzhan Vong control, with the Harbinger playing a critical role in the battle.
The commander of the Harbinger was General Garm Bel Iblis, a Corellian, who utilized the Star Cruiser as his flagship during his campaigns against the Yuuzhan Vong in the latter part of the war.
Harbinger made its debut appearance in Destiny's Way by Walter Jon Williams, a 2002 novel in The New Jedi Order series.