A warrior of great skill and renown in the Legiones Astartes of old, his name could be counted alongside such illustrious figures as First Captains Jago Sevatarion of the Night Lords, Ezekyle Abaddon of the Sons of Horus, Chapter Master Raldoron of the Blood Angels and Lord Commander Eidolon of the Emperor's Children.
Corswain was born on Caliban but was not originally one of the knights of The Order. Because of this, he was uniquely placed to bridge the divisions within the I st Legion between Terran-born and Caliban-born Astartes during its reformation into the Dark Angels under Lion El'Jonson's leadership. He was groomed to serve not any one Host or Order of the Legion but to command the respect and knowledge of all his Astartes.
Corswain became the Paladin of the 9th Order under Master Alajos during the Great Crusade. The finest swordsman in the I st Legion, he was the bearer of the Mantle of the Champion and one of only two Dark Angels ever to best Alajos. In time his reputation grew similar to that of other well-known Astartes of the era such as Raldoron and Sigismund.
Corswain was among the forces of the 9th Order that stripped Luther of his voidships after he disobeyed the Lion's orders to remain on Caliban in order to aid Horus and the other Imperial forces in the fight for the world of Zaramund in 970.M30. This was among the incidents that ultimately led Luther to embrace heresy.
During the opening years of the Horus Heresy, Corswain fought at Diamat alongside Lion El'Jonson against the Sons of Horus Legion and took part in the brutal campaign of the Dark Angels against the Night Lords called the Thramas Crusade in the Eastern Fringe of the Ultima Segmentum.
Two standard years into that campaign, the Night Lords' Primarch Konrad Curze attempted a parley upon the planet of Tsagualsa. Corswain accompanied Lion El'Jonson alongside his fellow Honour Guard member, Master Alajos. Curze was also accompanied by two members of his Honour Guard, First Captain Jago Sevatarion (Sevatar), and Lord Commander Sheng.
During the parley the conversation between the primarchs started amicably enough, until Curze slandered El'Jonson. In return, El'Jonson struck his former brother and a fight ensued.
The Night Haunter eventually gained the upper hand during the fight and began to strangle the Lion to death, but El'Jonson was rescued by the timely intervention of Corswain when the Paladin ran his sword into Curze's back, rendering him comatose.
During the fight, Sevatar decapitated Master Alajos, and Sheng helped his comatose primarch escape when reinforcements from both Legions arrived.
After the Battle of Perditus, Corswain was made seneschal to the Lion and given command of half of the remaining Legion to hunt down and eliminate First Captain Calas Typhon and his Death Guard splinter fleet while the Lion traveled with the other half to Ultramar.
Sustaining heavy casualties at the hands of the Death Guard, Corswain sent a small number of volunteers to Caliban with transports to bring reinforcements.
During the Siege of Terra, Corswain arrived at the edge of the Sol System with a Dark Angels fleet to rendezvous with the Imperial Fists' Phalanx where he proclaimed his forces were ready to fight for the Emperor.
Corswain survived the Horus Heresy to return to Caliban with the rest of the Legion. During the destruction of Caliban, he was among the first to make planetfall and do battle with the Fallen Angels.
- The Blade - The Blade was a master-crafted Terranic Greatsword possessed by the Dark Angels Legion, which was granted to Corswain by his mentor Alajos. It is said that the weapon was once raised aloft at Advex-mors by Grandmaster Urian Vendraig to incite the First Rangdan Xenocide. If so, then The Blade has been wielded by a Legion Champion in every campaign the Dark Angels have fought against those foul xenos.
- Armour of the Forest - The Armour of the Forest was a suit of masterfully wrought Artificer Armour that was struck from Terran steel by the Dark Angels Primarch Lion El'Jonson. This was done in the heart of Caliban's forests and the armour embodied the pragmatism of the Dark Angels Legion in its simple, utilitarian functionality and doughty endurance. It was eventually worn by Captain-Paladin Corswain, whose only adjustment was to enshroud himself in the Mantle of the Champion. This was only so that Corswain could obscure the symbols of his Order and Host, in order to better serve the entire Legion with purity of purpose as their Champion.
- Mantle of the Champion - The Mantle of the Champion was a ritual mantle of the Dark Angels Legion that was worn by Captain-Paladin Corswain over the Armour of the Forest he wore. This was only so that Corswain could obscure the symbols of his Order and Host, in order to better serve the entire Legion with a purity of purpose as their Champion.
- Age of Darkness (Anthology), "Savage Weapons," (Short Story) by Aaron Dembski-Bowden
- Angels of Caliban (Novel) by Gav Thorpe, Ch. 15
- Holder of the Keys (Audio Book) by Gav Thorpe
- The Primarchs (Anthology) "The Lion," (Short Story) by Gav Thorpe
- The Horus Heresy - Book Nine - Crusade (Forge World Series), pg. 170
- The Horus Heresy: Legions (PC Collectible Card Game) (Image)
- Saturnine (Novel) by Dan Abnett, Epilogue
- Space Hulk: Deathwing (Video Game)