Defender Wing functioned as a bomber wing within the New Republic Defense Force.
Established in 6 ABY, Defender Wing consisted of three squadrons of BTL-S3 Y-wing craft, all under the leadership of General Horton Salm.
Alongside the newly reformed Rogue Squadron, General Salm oversaw the training of Champion, Guardian, and Warden Squadrons on Folor. Following a humiliating defeat at the hands of Wedge Antilles's elite Rogues during a training exercise, a rivalry emerged between Salm's inexperienced pilots and the aces. To make matters worse, the Rogues programmed the Y-wings' main displays to show their new squadron crest whenever one was "shot down." This was later resolved when Emtrey, the Rogue Squadron quartermaster, supplied Defender Wing with a large quantity of new flight suits. Two weeks following the training exercise, Admiral Ackbar declared the wing fully operational.
The Battle of Vladet, the capital of the Rachuk sector, marked the wing's first significant engagement. During the operation, the starfighters were ambushed by the Carrack-class light cruiser Expeditious and the Lancer-class frigate Ravager. The Ravager was on the verge of destroying the Y-wings until Lieutenant Corran Horn, with his quick thinking, and a torpedo barrage from Warden Squadron, eliminated the Ravager.
The First Battle of Borleias also saw the wing's involvement. During the battle, the wing was stationed on the bulk cruiser Mon Valle. Despite being instructed to withdraw by General Laryn Kre'fey, the wing disobeyed and remained close to the Star Destroyer Emancipator. When the Imperials launched an ambush, Salm ordered the wing to re-engage, destroying several TIE Interceptors and rescuing the Rogues. A subsequent attempt to capture Borleias proved more successful, with Defender Wing and another fighter wing providing cover for Lieutenant Judder Page and his commando unit as they infiltrated and seized the base.
Defender Wing also participated in the capture of a station belonging to Warlord Zsinj at Yag'Dhul. Starting with that battle, Guardian Squadron switched from their older Y-wings to using B-wing starfighters.