Davian Thule was born on the planet Tartarus, but raised on Cyrene. He was also at one time the commander of the fourth company of the Space Marines
chapter, the Blood Ravens
During the dark crusade Thule was sent to planet Kronus
where he commanded the 1st, 2nd and 5th companies of the Blood Ravens in the interests of purging alien forces from the planet and securing relics on the planet which could reveal the secret origins of the Blood Ravens. When he arrived on Kronus, he sent orders to Governor-Militant Lukas Alexander for all civilians and Imperial Guard
to be evacuated from the planet so that the Blood Ravens could complete their purging of all life upon it. His orders were refused and bound by his orders to purge the planet, Thule was forced to order the killing of the Imperial Guard forces as well as all other aliens as part of the campaign on Kronus.
After the Blood Ravens' victory on Kronus, Thule arranged for the safe transportation of the survivors of the 1st Kronus Regiment of the Imperial Guard off of the planet. Thule and a Blood Ravens Chaplain also honored the dead body of Lukas Alexander, but were forced to execute all soldiers of the 1st Kronus Regiment's 5th company due to their rebellion against the rest of their regiment. It was also the actions of Thule and the Blood Ravens 2nd company, which were under his command, in wiping out the Necrons
of Kronus at Thur'Abis Plateau, which led to the 2nd company later adopting the motto "victory over death". Thule had personally planted the bomb which wiped out the Necrons deep within the catacombs of the plateau, but had suffered serious wounds in the final battle with the Necron Lord of Kronus, including losing his right eye which had to later be replaced with a bionic substitute.
Thule was later made commander of Space Marines operations in sub-sector Aurelia, charged with the duty of protecting the Space Marine recruitment worlds Calderis
and Typhon Primaris
and was very closely involved with the rest of the Blood Ravens in the sub-sector. After the successful defense of Argus Gate against the Orks
Thule was caught in the surprise Tyranid
attack on the Blood Ravens and became severely injured and poisoned. By raiding various Tyranid hives and taking samples from them, the Blood Ravens eventually managed to find a cure for Thule and he returned as a Dreadnought
to aid the chapter in defeating a Tyranid Hive Tyrant on Typhon. It is also later revealed by Cyrus
during the events in the Aurelia sub-sector that Thule found records of the Blood Ravens origins on Kronus but destroyed them after reading.