Tulian Aquila

Brother Gaius: "Have you given up hope, Sergeant?" Sergeant Aquila: "Any optimism I harbored died with the Traitor's first salvo. The Word Bearers have hit us at our most vulnerable. It is likely the Ultramarines Legion will die on Calth."

- Sergeant Tulian Aquila, Battle of Calth

Tullian Aquila was the founder and first Chapter Master of the Doom Eagles, a Second Founding Successor Chapter of the vaunted Ultramarines Legion.

History
Brother Septival: "So you have hope for the future of the Imperium after all." Sergeant Aquila: "Hope is but the first step on the road to disappointment, Brother. You can fight for hope if you wish. I will fight to bring honour to the dead."

- Sergeant Tulian Aquila, Battle of Calth

Tullian Aquila was a veteran battle-brother of the Ultramarines Legion having served both during the Great Crusade and the Horus Heresy eras. He served as a Sergeant during the Battle of Calth, stationed alongside his company at the city of Ithraca. When the traitorous Word Bearers Traitor Legion struck after taking control of Calth's orbital defences, only Sergeant Aquila and two other Battle-Brothers survived the orbital barrage. During the subsequent fighting, Aquila was moved by the sacrifice of one of his Battle-Brothers and came to the realisation -- even though he himself was already dead -- that he had a duty to protect the innocent and to suffer, so that they did not have to.

Later on, then-Captain Aquila would go on to become the founder and first Chapter Master of the newly created Doom Eagles Chapter during the Second Founding. The Doom Eagles quickly embraced their Chapter Master's sense of fatalism, and came to accept that death was inevitable, and that every mission performed on behalf of the Emperor must be pursued with both fervour and zeal in defence of the Imperium and its people before one's life was spent.