The Gleipnir was developed in the aftermath of the Leasath Civil War, under Diego Gaspar Navarro's direction. It was developed jointly with the Fenrir, being designed with the ability of obtaining battle data to refine the fighter. The Gleipnir was the second giant aircraft created by Leasath, followed by the Gandr, its own prototype. A week prior to the invasion of Aurelia, Navarro personally designated Captain Frank Burlington as the commander of the ship.
Leasath deployed the Gleipnir in Aurelia shortly after the destruction of Gandr, acting as the linchpin of Navarro's invasion, who used its firepower to conquer most of the country within ten days. The city of Santa Elva, on account of the Lenal River running through it, became the base of operations of the fortress after its capture. On the eleventh day of the invasion, Navarro ordered the deployment of the Gleipnir to decimate the Gryphus Squadron during a failed bombing attack on Aubrey Air Force Base, killing most of the unit's members with a Shock Wave Ballistic Missile strike; the event was witnessed by civilian crowds nearby Cape Aubrey.
As the Aurelian counter-strike continued, it was eventually determined that the conditions were optimal for a direct attack on the Gleipnir itself. The ship, which retained fully functional stealth and SWBM launching ability, was attacked by Gryphus One in Santa Elva as it attacked ground forces at the Stand Canyon.
Gryphus evaded the fortress' attacks and disabled its stealth system and destroy its SWBM launch ports. In desperation, Burlington ordered the ship's crew to fire the Shock Cannon at Santa Elva. However, Gryphus One destroyed the cannon with missiles, causing its inner systems to fail, leading the Gleipnir into plunging into the Lenal River, miraculously avoiding serious damage to the city. Some of its crew survived the crash and were taken prisoner by Aurelian ground forces.
Like other giant aircraft from the Strangereal world, the Gleipnir is intended to overwhelm enemy targets with its heavy firepower. Because of its gargantuan size, it cannot use runways to take off, thus necessitating its development as a flying boat. The ship is armed with Shock Wave Ballistic Missile launchers, a Shock Cannon in the ventral area and an optical camouflage system. Despite its imposing size and role, the Gleipnir is considered an "airborne fortress" instead of a heavy command cruiser.
- The Gleipnir is named after a magical bind from Norse mythology, which restrained the legendary wolf Fenrir. The name matches the aircraft's link with the Fenrir.