Along with Griffin and Ifrit, Leviathan participated in Operation Menelaus, commanded by Aiden Meyers. After the operation, the carrier returned to Spirit, before it became part of the search and rescue team, looking for Griffin. It arrived in the Phylent system only 30 minutes after the conclusion of the battle between Griffin, Ifrit and Dragon, and then lead the surviving CSN carriers home.

Leviathan was the closest CSN vessel to the Coyote system when Ifrit was shot down and Mythos was invaded. Acting captain Aiden Meyers took the carrier into the system to ascertain the size and strength of the Pandoran forces surrounding the planet, before he was forced to retreat as soon as he discovered he was outnumbered.

The ship joined the battle in Coyote, along with a number of UNF vessels, including Talos. Leviathan sustained moderate damage during the battle, but escaped with the allied forced when the Tachyon Star Bombs exploded on Grendel's Mother.

Leviathan remained under the captaincy of Aiden Meyers throughout the Pandoran War, serving mostly on the defence lines in the Independent and Helios systems. Leviathan took part in phase two of Black Widow, being one of the few ships to escape from the Adetton system. It was defended during jump by Chaz Koonan and Simon Dodds, who fought off a number of pursuing Pandoran starfighters, that were attempting to force the ship out of jump.

The carrier remained in Helios when Parks split the allied forces in two, helping to counter the Pandoran forces that arrived in the systems. Both Kelly Taylor and Estelle de Winter were posted to the ship during that time.

Leviathan formed part of the defence line at Alpha Centauri in late 2624, acting alongside Talos and Amarok. It survived the battle, falling back to Sol where it took part in the final battle for the Solar System, on 26th December. As part of a push by the allies to encourage Dragon to enter the system, Leviathan moved up from its midfield position and deep into the enemy ranks, shoot down as many opposing capital ships as possible. The carrier was destroyed during the attempt, though Meyers survived, the bridge crew ushering him to an escape pod when he lost consciousness.