The ship was first used in the Second Battle of Earth where it was part of a failed attack by Lord Hood on the Eiffel Tower. Along with the UNSC Aegis Fate and Lord Hood's Command ship, Terrantime's Advance, the Forward Unto Dawn broke through the Covenant Anti-Air Defences and attacked the Eiffel Tower with continuous MAC blasts. This did next to nothing however and the crews of the ships looked on in horror as the portal to the Ark opened.The ship joined with the Elite fleet and flew through the portal with Master Chief, Arbiter, Guilty Guilty and Johnson on board. During the battle it bombed several Brute ships along with the Aegis Fate and dropped off a continuous supply of tanks, weapons and ordnance for the ground teams to use. After its commander was killed in the attack on the Citadel the Forward Unto Dawn was abandoned by its crew who were preparing to flee the Ark. However, Johnny still had some unfinished busines. He and Arby infiltrated High Charity and rescued Cortana who they wanted to use to activate a new Halo that had been discovered, in order to wipe out the Flood. They flew the frigate to the control center of the new Halo and parked it close by. However, after they had activated the ring the Halo began to fall apart. Johnny, Arby and two of Arby's buddies had to drive a Warthog or two across a rapidly disintergrating plain to reach the frigate, and they only just made it in time.
As they skidded into the hangar bay Johnny fell out of his Warthog and as Arby and his pals skidded through a door a massive pile of crates fell on top of them. As Arby struggled to make an opening for Johnny, he signalled for him to go. After a moment of hesitation Arby left and, with help from his pals, flew the frigate away from the Ark.
However, as they went through the portal, it collapsed, tearing the ship in two. Johnny and Cortana were stranded in space but Arby and his chums made it back to Earth, crashing into the sea. Johnny put himself into cryogenic stasis and four years later what was left of the Dawn crashed onto Requiem. Despite being a wreck, it was still able to fire a well-aimed torpedo (with a little push from Chief) which quite literally blasted a Covenant Ship to pieces.