The Yavin Coalition represented a combined task force. It was brought into existence by the Jedi Grand Master Satele Shan alongside Darth Marr, who led the Dark Council. The purpose was to address the danger presented by Revan together with his followers back in 3637 BBY.
Revan's overarching objective was to force the Sith Emperor Vitiate into a corporeal form on Yavin 4 so he could be eliminated. However, he also orchestrated a trap intended for both the Imperial and Republic fleets positioned above Rishi. Nova Blades pirates were contracted to target shipping lanes, with the goal of diverting hyperlanes to entice the fleets into the system. Once the fleets arrived, a signal jammer was set to disrupt communications within both fleets. Simultaneously, saboteurs infiltrated the vessels to compromise their systems, with the intent of triggering a mutual annihilation. Following this, Revanite ships were planned to eliminate any remaining survivors.
The Revanite scheme nearly came to fruition. However, following the engagement in the Battle of Rishi between two fleets commanded by Jedi Grand Master Satele Shan and Dark Council's acting leader Darth Marr, the jammer on the planet's surface was deactivated by the associate of Lana Beniko and Theron Shan. They then made contact with the fleets, exposing the Revanite deception and providing a complete list of traitors within both fleets as evidence. This information led both commanders to issue a ceasefire. Subsequently, they convened at a neutral site in Raider's Cove. Recognizing the threat posed by the potential rebirth of the Sith Emperor to all life, both sides agreed to set aside their differences to prevent Vitiate from consuming all life in the galaxy.
Largely acting independently, without the sanction or awareness of others in either the Galactic Republic or the Sith Empire, Darth Marr and Grand Master Shan established the Coalition using elements of their respective fleets. They journeyed to the moon of Yavin 4 in an attempt to thwart Revan's plans. The Coalition set up a Command Post near the Revanite position. Initially, they were limited in what they could achieve, as soldiers from both sides were suspicious of each other and struggled to collaborate effectively. A network of sensor beacons was deployed along the perimeter. This provided the Coalition with surveillance of Revanite activities, as well as a safeguard against potential betrayal.
It came to light that the Revanites had seized control of an Imperial Guard Academy. An incursion into this academy resulted in the capture of Commandant Iven, a surviving member of the Imperial Guard. Iven revealed that the Revanites were using the Temple of Sacrifice as their headquarters. He also disclosed Revan's intention to use an artifact capable of resurrecting the Sith Emperor, but at the cost of all life on the moon, except for those within the Temple. Despite the escalating conflict between the Revanites and the Coalition, Satele Shan and Darth Marr both sensed a significant light-side presence on the moon. This was later identified as the Force ghost of Revan. Following the battle of the Foundry, Revan's being had split into two distinct halves, representing his light and dark aspects. Revan's light-side aspect was capable of merging with the Force, but could not do so without his dark counterpart, who still existed in physical form and was the one endeavoring to revive Vitiate.
The intricate locking mechanisms of the Temple were disabled, but a substantial force of Revanites still stood between the Coalition forces and the Temple itself. Once the long-standing rivalries between the Republic and Imperial soldiers had been resolved, both sides were able to function as a cohesive unit. A strike team comprised of eight of the Republic and Imperial's finest stormed the Temple. This team engaged the remaining Revanite Commanders, as well as the native creatures of Yavin IV, ultimately defeating Revan and destroying a HK-47 unit. Revan's ritual was halted, and the artifact was destroyed. However, Revan managed to escape the Temple, retreating to a nearby sanctuary. To end his threat permanently, the Coalition leadership, including Darth Marr, Satele Shan, her son Theron Shan, Sith Lord Lana Beniko, Wookiee smuggler Jakarro, and Shae Vizla, who concluded her exile on Rishi to confront a worthy opponent, went to confront Revan directly.
The Coalition forces engaged Revan in open combat and ultimately defeated him. However, their victory was short-lived. The extensive fighting on the moon caused enough death to enable Vitiate's return to life regardless. His spirit departed the moon without inhabiting a physical body. Meanwhile, the dark half of Revan was confronted by his light counterpart, who persuaded him to rejoin and become one with the Force.
Despite the Coalition's success, it was acknowledged that Vitiate's return posed a universal threat. Although the Republic and the Empire remained at war, Marr and Shan agreed that they would reestablish their alliance upon Vitiate's next sighting. For the time being, the Coalition was disbanded, and both fleets returned to their respective factions. However, both sides maintained small garrisons on the moon to address the remaining pockets of Revanite activity. Both leaders were unable to react swiftly enough when Vitiate reemerged on the Sith world of Ziost, where he executed his ritual that extinguished all life on the planet. Darth Marr subsequently led a strike team in pursuit of their former Emperor into Wild Space, inviting many veterans of Yavin to join them. Unfortunately, they encountered the hidden Eternal Empire of Zakuul. During the first skirmish with the Eternal Fleet, Darth Marr's task force was largely annihilated, with few survivors. Marr himself was captured and executed by his former Emperor.
Even though the Coalition was dissolved, several of its former members would later establish what became the Eternal Alliance. This was based on the Coalition, as they fought against the Eternal Empire.