During 3 ABY, the Coyerti campaign unfolded when the Coyerti species sought sanctuary from the Galactic Empire. The Rebel Alliance dispatched Twilight Company to assist them. In the midst of the conflict, Everi Chalis, a governor who had defected, shared crucial intelligence about a secret biotoxin facility. A Rebel squad successfully destroyed this facility, but they were exposed to toxins during the mission, although they made a swift recovery. As the battle concluded, the Coyerti military united to obliterate the Imperial garrison.
Prior to the campaign's commencement, the Rebel Alliance had been in retreat from the Mid Rim for a period of 96 days. The Rebels suffered losses on numerous planets, leading to their forces retreating into the Outer Rim. The 61st Mobile Infantry, famously known as Twilight Company, was deployed to provide cover for other Rebel battlegroups and to safeguard the Coyerti during their breeding season. During this time, they were particularly vulnerable to Imperial bioweapons, despite their usual resilience. Securing Coyerti would strengthen the territory between the Empire's domain in the Mid Rim and the far reaches of the galaxy for the Rebellion.
Twilight deployed dropships carrying squads to various locations across the planet. Hazram Namir's squad immediately engaged in combat, launching an assault on an Imperial encampment. Gadren, who aggressively charged into the Imperial stormtroopers, narrowly avoided death due to a defective grenade that failed to detonate at his feet. The attack progressed more smoothly afterward, as Namir's squad coordinated with Sergeant Zab's squad to attack an Imperial scout camp. The camp was newly established and completely unprepared for the assault by the two squads. Attacking from multiple directions, the squads overwhelmed the troopers within ten minutes. Subsequently, they planted explosives and quickly retreated as TIE/sa bombers arrived to destroy the camp.
The following day, Namir and his squad were traversing a swamp for five hours when they received a message from Lieutenant Sairgon. The message indicated a change in plans, with a dozen Rebel squads led by Carver assigned to capture the fort. Brand later mentioned that they had successfully destroyed it. Later, Namir received instructions to locate and eliminate an AT-ST. His squad had only three grenades in total. Garden's initial grenade missed its target, but the second grenade inflicted noticeable damage to the AT-ST's legs. While attempting to enter the cockpit, Brand injured her ankle in a fall. After a day-long engagement, Namir and his squad managed to submerge the AT-ST in the swamp.
On the fourth day, Captain Micha Evon decided to validate the information provided by the former Governor Everi Chalis. Namir's squad was tasked with destroying an Imperial bio-weapon facility known as the Distillery, which would significantly hinder the Empire's progress on Coyerti. His squad marched the entire day to reach the facility and infiltrated it the following day. Brand detonated a small explosive on a blue crate, triggering an alarm. As the staff evacuated the bunker, the team entered, and Roach, one of Twilight's newest members, shot one of the fleeing men as they planted explosives. Thirty minutes later, after the squad had safely retreated, the bombs detonated, destroying the Distillery. While en route to the evacuation zone, the team discovered they had been exposed to a bioweapon. Garden appeared to be immune and established a camp near the evacuation zone while the others rested. The dropship was delayed, requiring them to wait several days for its arrival. Subsequently, they received medical treatment aboard the Thunderstrike. Meanwhile, other Twilight forces under the command of Ajax were pinned down by a walker, with their air support, including several X-wing starfighters, unable to secure a clear shot. However, a rhythmic drumming sound emerged, and a massive Coyerti army appeared. The Imperial lieutenant in charge surrendered, and the rebels celebrated their triumph.
The Coyerti campaign was one of several rearguard actions undertaken by the rebels that week. Multiple battle groups launched attacks on Imperial worlds to facilitate the evacuation of the Alliance Fleet from the Mid Rim. Other battles involved the 21st on Bestine IV and Bitter Pill Company, a unit that lost its troop transport during their engagement. Coyerti stood out as one of the Alliance's few victories during the final Mid Rim Retreat. Losses included battles at Hope Station, Unroola Dawn, and Talrezan Four.
The Coyerti campaign is depicted in the 2015 novel Battlefront: Twilight Company, authored by Alexander Freed.