The original members of the Ultima Squad were killed in a Tyranid attack that took place in the underhives on Algol. While the fight continued, Captain Severus received an urgent distress call from the 5th Company of the Imperial Fists garrisoned on the Imperial Shrine World Mithron.
Being short of combat ready resources, he promoted ten Scouts from Initiates to fully fledged Space Marines. These ten Battle-Brothers then were given the name Ultima Squad and accompanied him on the rescue mission to Mithron.
- Sergeant Crastor - Squad leader
- Brother Boreas - Standard Bearer
- Brother Decius
- Brother Hypax
- Brother Junor - Flamer wielder
- Brother Lycos - Land Speeder pilot
- Brother Maxillius
- Brother Proteus
- Brother Remulus
- Brother Verenor