Aegis Fate

The UNSC Aegis Fate was a frigate assigned to the UNSC Home Fleet and was one of the last remaining UNSC ships in the fleet by the time Master Chief returned to Earth. It, along with the UNSC Forward Unto Dawn and another vessel, led Lord Hood's failed attack on the Eiffel Tower before it escaped into slipspace. Hood then decided to turn his attention towards the Covenant and attack Truth's Forerunner Dreadnaught as well, which also escaped into Slipspace.

Because the commander of the Fate wasn't a complete coward (like Hoody Hood was) he decided to aid Miranda Keyes and the Elites in the Battle of the Ark, whilst Hood stayed behind on Earth to 'hold out' against the mythical Flood army that was apparently approaching. How he intended to do this with only one ship is mystifying, however, I digress.

The Fate led the initial charge on Brute occupied strongholds all around the Ark. It dropped several waves of UNSC forces into desert areas around the Epitaph tower of the Ark, including Sandtrap Camp and the mysterious 'Citadel'. From there, the Fate established a foothold on the Ark and pelted the Brutes with MAC blasts from orbit.

Taking advantage of the annihilation of the Brute fleet by the Elites, the Fate gathered all the suviving UNSC Marines following the deactivation of the Halo Array by the Arbiter and the Master Chief. The ship flew into the hangar of the Shadow of Intent and followed the rest of the Elite fleet to Earth. The Fate was again used during the attack on Earth by the Didact, where it destroyed a trillion Prometheans before sitting out for the rest of the battle as it was so pathetic. The Infinity did all the work anyway.