The Occlusiad War, also known simply as the Occlusiad, was a major conflict that raged from 550-560.M37 on the northwestern fringe of the Segmentum Obscurus between the Imperium of Man and the rogue Tech-Priests known as the Apostles of the Blind King. The conflict was only ended through the efforts of the Imperial Navy, Mars itself and the founding of the heroic Dark Hunters Space Marine Chapter.
In 550.M37, the northwestern fringe of the Segmentum Obscurus was ravaged by the apostate Adeptus Mechanicus Heretek cult known as the Apostles of the Blind King. These cultists were Tech-priests who viewed humanity as an affront to the Machine God. The Apostles uncovered wondrous artefacts lost in the Dark Age of Technology that allowed the creation of supernovae from the hearts of living suns.
Recently discovered archives describe a battle tank used by the Space Marine Legions during the Great Crusade that was similar to one fielded in large numbers by the followers of the Blind King during this terrible conflict. This medium-sized tracked vehicle was equipped with a remotely operated turret-mounted weapons system thought lost since the time of the Great Scouring, and it outclassed many of the tanks fielded by the Imperium against the Hereteks serving the Blind King.
During one notable engagement, which came to be known as the Battle of Bloodsteel, the Heretek forces of the Blind King assaulted the Chapter Homeworld of the newly formed Dark Hunters Space Marines and the Warpsmith Hilghar, who employed Daemon Engines in vast numbers, as well as the Chaos-corrupted Warlord Titan Repellus. Though the Dark Hunters deployed and managed to successfully contain the assault by the Warpsmith and his formidable forces, the Chapter sustained heavy casualties.
As the conflict escalated, constellations were forever changed as the Apostles purged the outer Segmentum Obscurus of human-settled worlds by forcing many stars to go nova. War raged for solar decades, until the Navigator Joyre Macran discovered the palace-warship of the Blind King hidden within a fold of Warpspace. Escaping with this knowledge, Macran guided the Emperor-class Battleship Dominus Astra to the palace's location. The Blind King was killed by the Dominus Astra's Lance batteries when they pierced his palace-warship's hull, and without his psychic prescience the Apostles were swiftly overcome by Imperial forces.
- Codex: Adeptus Mechanicus (8th Edition), "The Quest for Knowledge," pg. 33
- Codex: Adeptus Mechanicus - Skitarii (7th Edition) pg. 37
- Codex: Space Marines (6th Edition), pg. 39
- Cult Mechanicus Painting Guide - Crusaders of the Machine God (Painting Guide), pg. 34
- Imperial Armour Volume Two - Second Edition: War Machines of the Adeptus Astartes, pg. 11
- Warhammer 40,000: Rulebook (5th Edition), pg. 125
- Dark Hunters - The Blind King (Short Story) by Paul Kearney