Around ten years prior to the Clone Wars, the Galactic Republic dispatched a contingent of Jedi and Judicials on a quest to liberate captives held by usurpers residing on the planet of Halcyon. Upon landing, the usurpers disrupted the Republic forces' communications, resulting in one Judicial team becoming separated for several days. Ultimately, the Jedi successfully freed all the hostages, and the lost squad was reunited with the Republic forces, a feat made possible by the cadet Wilhuff Tarkin of the Judicials.
A decade before the Clone Wars, a group of technologically advanced would-be usurpers on the planet Halcyon grew dissatisfied with their world's status as a member of the Galactic Republic. Desiring self-governance for their world, they abducted several key figures in Halcyon's planetary leadership and confined them within a secluded fortress, preparing for potential conflict. The Republic attempted diplomatic negotiations with the usurpers for the release of their hostages, but these talks proved fruitless. Consequently, the Galactic Senate ultimately authorized members of the Jedi Order to journey to Halcyon to negotiate, resorting to force if necessary. Eighty members of the Republic's Judicial Department were chosen to accompany them, including inexperienced recruits like Wilhuff Tarkin.
During their voyage to Halcyon, the Republic forces traveled aboard two cruisers, where the Jedi dedicated their time to honing their skills with their lightsabers, a spectacle keenly observed by Tarkin. Upon their arrival on Halcyon, the Judicial Forces were divided into four teams by the Jedi. One group was selected to accompany the Jedi, while the remaining three were strategically positioned to prevent the usurpers' escape through a series of low mountains situated on the far side of their fortress. Immediately after the Judicials deployed, the usurpers disabled Halcyon's global positioning satellites and blocked all surface-to-air communications, effectively isolating the teams from their cruisers, the Jedi, and each other.
The commander of Tarkin's team, one of the groups tasked with preventing escape, opted to advance through bogs and forests toward the usurpers' location, relying on regional maps stored on his datapad following the communications blackout. For a period of three days, the team struggled to reach the fortress, their progress hindered by adverse weather conditions, mudslides, and unexpected tree falls, resulting in them retracing their steps multiple times. By the fourth day, rations were depleted, and the team's morale plummeted, significantly impairing teamwork. While the team paralleled a wide, rapidly flowing river for several hours, Tarkin carefully analyzed the water's flow and allowed the team to pass a shallow region they could have crossed. He then waited for the team to begin arguing how deep the river was before wading into the middle to show its depth. Following this demonstration of intelligence, the team's commander kept Tarkin by his side and eventually surrendered point to him, entrusting the recruit with leading the lost Judicials.
Now in command, Tarkin utilized Halcyon's suns and moons for navigation, guiding them towards a more open area of woodland. Along the way, he imparted knowledge of hunting and outdoor survival techniques to his comrades. After an additional three days of travel, Tarkin estimated their proximity to be within five kilometers of their destination, and relinquished control back to the commander for the final leg of the mission. The team arrived shortly after the Jedi had successfully rescued the hostages, with no killed. Their unexpected arrival astonished the Jedi, who had lost hope of finding the Judicial team alive after search parties failed to locate them.
Following the mission's conclusion, the cadets in Tarkin's team initially hesitated to disclose the events that transpired during their absence. However, word of Tarkin's heroic actions and leadership eventually spread, and he received the recognition he deserved. Upon returning to the Judicial Academy, Tarkin experienced a surge in popularity due to the incident, with a group of cadets forming around him. As Tarkin participated in further missions similar to the one on Halcyon, he cultivated a reputation as a capable leader. However, he eventually departed from the Judicial Department to pursue galactic politics after a division arose within the organization regarding opinions on the Republic and its laws.
The Halcyon mission was initially detailed in the novel Tarkin, authored by James Luceno and published in 2014.