Icebreaker was stationed on board the UNSC Infinity when the vessel returned to the Epoloch system to recapture Requiem from Covenant forces. At some point during the battle, the team was lost behind enemy lines and assumed KIA. The team was captured by Covenant and interred within the massive shipyard at REQ//0923-4303. Later the Covenant would succeed in subduing and capturing a Spartan fireteam after a prolonged firefight. The captured Spartans (who were part of Fireteam Crimson) eventually broke free of their restraints and killed the team of Zealots guarding them. In an attempt to steal a Covenant vehicle with which to escape, the Spartans found their way into the chamber where Icebreaker was being held. The squad leader, Lieutenant Murphy, was able to use his knowledge of Covenant ordnance to hijack a docked Phantom and fly Crimson and Icebreaker to safety. Along they way, they made several stops to destroy Covenant installations and secure strategic locations. The teams then hastened back to the Infinity, which had come under attack from an armada of Jul 'Mdama's Covenant.
It is unknown what happened to Icebreaker after attack on the Infinity, but Murphy continued to aid Fireteam Crimson throughout the duration of the campaign. Murphy was one of the last of all UNSC personnel to leave Requiem, evacuating Fireteam Crimson by Pelican shortly after the Spartans de-activated a Slipspace anchor on the surface and immediately before Requiem was destroyed along with its star.
- There are several factors that indicate that Icebreaker might be a special forces team. Every member of the squad wears heavy armor, which isn't seen in any other Marine squad in Halo 4. Secondly, the team was captured far behind enemy lines, suggesting that they were scouts or forward operators. Finally the team leader, Lieutenant Murphy, is a skilled pilot of both UNSC and Covenant aircraft, suggesting that he has received extensive training.
- While unconfirmed, it appears that all members of Icebreaker were killed at some point before the attack on the Infinity. The team is only seen in-game during the first chapter of Spartan Ops Episode Six, during which it is possible for all members of the team to die but Murphy. The Marines are not seen during any of the following missions, and even if they had survived, they would likely have been killed when their Phantom crashed into Infinity's hangar.