Iron Warriors - The Invasion of Ultramar and the 13th Black Crusade: With his army assembled, Honsou was finally ready to unleash his audacious plan for revenge against Uriel Ventris by completely destroying the Realm of Ultramar during what became known as the Invasion of Ultramar in 999.M41. He would enact his plan with the help of the Daemon Prince M'kar the Reborn, who had once been Maloq Kartho, a Dark Apostle of the Word Bearers Traitor Legion during the Horus Heresy.Learning of the vile daemon's long-standing hatred for the Ultramarines, Honsou was able to enlist the aid of Abaddon the Despoiler's damned seer Moriana to help free the daemon's spirit from its prison, which had been trapped within the Warp core of the Star Fort Indomitable by the Ultramarines' Chapter Master Marneus Calgar decades earlier, in 935.M41.With his formidable army of Chaos Renegades, Honsou easily captured the Star Fort and was able to free M'kar from his prison. The Daemon Prince then possessed the armoured Dreadnought chassis of Brother Altarion, an Ultramarines Astartes assigned to guard the fort. M'kar used Altarion's once-sacred shell as his host-body in order to remain in the material universe. With his army ready, Honsou's forces first struck within the Realm of Ultramar on the arid Imperial Agri-World of Tarentus. The newly freed M'kar bound the Indomitable to a Warp Gate and called forth a huge army of daemons to attack the cities of the planet from within, slaughtering the entire world's population. When the Ultramarines Chapter responded to the dire threat that Honsou's forces presented, the Warsmith left a trap for them in the planet's capital city of Axum, which nearly annihilated Captain Uriel Ventris and the entirety of his 4th Company.After their success on Tarentus, Honsou's forces next assaulted the Imperial Ocean World of Talassar. After laying siege to the planet, M'kar quickly forced himself into a position of shared command of the Warsmith's Chaotic army and divided its forces amongst the various Chaos Champions, a situation neither Chaos Lord could tolerate for any length of time. The Forces of Chaos gathered by Honsou were dubbed by the Daemon Prince as the "Bloodborn", much to the Warsmith's resentment. Each subordinate commander was then assigned a different strategic target.M'kar convinced Honsou to travel to Ventris' homeworld of Calth, with explicit instructions from M'kar to destroy the Tomb of Ventanus -- the famed Ultramarines Captain who slew the Daemon Prince when he was still a mortal and a former Dark Apostle of the Word Bearers during the Horus Heresy. M'kar could not himself go near the tomb, which radiated the power of Imperial faith in the Emperor and was thus anathema to a creature of the Warp.Armed with the knowledge of Ventris, the clone known as the Newborn was able to find the location of the subterranean tomb within the Cavernas Draconi on Calth. Honsou and his ally Grendel were led by the Newborn and eventually discovered the tomb's exact location. As they prepared to destroy it, the keen mind of Honsou perceived that there was more to M'kar's reluctance to come near the world of Calth than the foul creature had admitted. Therefore, the Warsmith decided to investigate further and soon discovered that there was an artefact, a Combat Knife, buried with the long-dead Ultramarines captain that was known as the Shard of Erebus.Honsou realised that the simple blade was capable of badly harming the Daemon Prince because of the faith that had been invested within it after so many millennia of devotion. But before the Warsmith could capitalise on the newly acquired weapon, Captain Ventris and a Command Squad of Ultramarines arrived and began attacking Honsou's forces. Honsou tasked the Newborn to kill Ventris, but in the ensuing battle the Ultramarines captain was able to defeat his corrupted clone.At the height of the battle, the Iron Warriors were overwhelmed and defeated by what appeared to be the ghosts of Captain Ventanus and his fellow Ultramarines that were housed within the tomb. With his men dead and his quest for vengeance foiled, Honsou activated the trigger for explosives intended to destroy the tomb. The resulting explosion buried Captain Ventris and his men, but he and the majority of his allies managed to survive the explosion and subsequent cave-in.Upon further investigation, the body of Honsou was never found. However, there is ample evidence that indicates that the wily Iron Warrior may have survived. A drilling machine that had been used by the Iron Warriors to reach the tomb complex had also disappeared, indicating that Honsou had probably escaped his well-deserved fate, yet again.M'kar survived to eventually face Marneus Calgar once more on the planet Talassar, but his essence was completely annihilated after Calgar struck him with the Shard of Erebus -- the same blade that Captain Ventanus had used to slay M'kar's human form of Maloq Kartho on Calth during the Horus Heresy.