Sometime following the Battle of Yavin, the Rebel Alliance executed a seizure of the Imperial I-class Star Destroyer called Harbinger.
The Millennium Falcon, with Han Solo, Leia Organa, Chewbacca, Sana Starros, and C-3PO aboard, initiated two bombing runs against the Harbinger. The initial attempt failed, but the second successfully penetrated the hull, creating a small opening in Sector 19-A. This breach provided access to the main engine reactor of the Star Destroyer.
Piloting an X-wing starfighter, Wedge Antilles launched another bombing run with the objective of hitting the reactor to cause an overload. His torpedoes missed their intended target, so Luke Skywalker piloted his own X-wing into the destroyer and achieved several hits with laser cannons, resulting in the reactor overloading.
With all Imperial personnel in the vicinity either dead or unable to act, and the reactor on the verge of overloading before the emergency engineers could disable it, the Harbinger's admiral gave the order for the crew to abandon the ship.
As the shuttles commenced their departure from the crippled destroyer, the Falcon touched down in the hangar bay, and the hijackers ejected the reactor. R2 ejected the overloading reactor before it exploded and the Star Destroyer jumped into hyperspace. Upon its detonation, the departing shuttles informed Imperial High Command of the Harbinger's loss, and the admiral considered suicide upon realizing that Darth Vader would hold him personally accountable.
Imperial High Command remained unaware of the Harbinger's survival in rebel hands for at least a week, though several TIE fighter patrols were deployed to investigate the disappearances of Imperial shuttles within the sector. However, this did not escape the attention of Darth Vader, who dispatched Task Force 99 to capture Admiral Verette in order to reclaim the destroyer and capture Skywalker. Meanwhile, the rebels employed the ship to break the siege on Tureen VII.