- "It has been calculated that there is one Space Marine for each of the million worlds of the Imperium, and that that number, though small, is sufficient to protect humanity from the foul schemes of the alien, heretics and the powers of the Warp. But if even only one of those brothers should turn from the light of the Emperor's Truth and fall upon his fellows like a thing run mad, how can it be enough?"
- —From the treatise Quis Custodiet Ipsos Angeles Mortes? by Gideon Lorr, Inquisitor, Ordo Hereticus
The Constantinus Iconoclasm was a rebellion led by the former Sergeant Constantinus of the 4th Company of the Sons of Guilliman Space Marine Chapter, which had been charged with freeing the world of Nova Terra, located within the Segmentum Pacificus, from a Tyranid attack by remnants of the Hive Fleet Leviathan. He was a part of a handful of Astartes units left behind on Nova Terra to combat any resurgent Tyranid organisms that had survived the war, and to monitor the populace for signs of Genestealer or other Tyranid infiltration or infection. For three standard years Sergeant Constantinus led his squad on endless patrols through the cave systems of Nova Terra's volcanic plateau where the Tyranids had made planetfall, cleansing nesting broods with Flamer and Chainsword, not once seeking reward. However, when rumours led Constantinus to a possible Genestealers infection in the Nova Terran capital city of Cirtus, he found a growing Genestealer Cult had pervaded the city's ruling aristocracy.
As righteous as ever, Constantinus and his squad hunted down the infected nobles and their families and swiftly ended the threat. Far from being grateful, the people of Cirtus were enraged by the summary executions of their leaders and rose up in revolt. Two dozen Battle-Brothers of the 4th Company of the Sons of Guilliman had sacrificed themselves for this world, this Nova Terra, only for those who had remained behind to battle the tyranid threat -- unremembered and unrewarded -- to now have to suffer this final dishonour. That had been the final disgrace, the final injurious slight that had pushed Sergeant Constantinus beyond the brink. It was more than any mortal man, or immortal Adeptus Astartes, should ever had to endure. If the scum of Cirtus city wanted rebellion, to see their world burn, Squad Constantinus would light the fire for them.
There were those who had already sworn themselves to the sergeant, having seen what Constantinus and his brethren had wrought within the city sectors -- including Imperial Guardsmen who had seen their fellow soldiers die to save Nova Terra from the Tyranids, looters, rioters, the dispossessed, former servants of the Ecclesiarchy, and the members of the Adeptus Arbites stationed on this world. They appreciated what the sergeant and his men had done, what they had been forced to do and why. They willingly followed Constantinus, and even went so far as to call him "the Liberator." Constantinus led his squad on search and destroy missions throughout Cirtus, destroying entire city sectors. Soon the city was ablaze and the fume-choked avenues were awash with blood and rioting mobs, the palaces of the nobles nothing but charred ruins. Constantinus eventually turned upon those within his own squad who tried to stop him from carrying out the massacre and cut them down. He then declared himself the new ruler of Cirtus, decrying the Emperor of Mankind and His minions, claiming that his own Chapter had turned him into a murderous monster, and swore that he would lead the people of Cirtus to freedom and a better future outside the Imperium. His conviction proved infectious. The old order on the world was thrown down, the emblems of the Imperium destroyed and defaced while statues of Constantinus the Liberator were raised in their place. Once the city was taken, the revolt spread from city to city, until finally the Liberator stormed the mansion of the world's Imperial Commander at the head of an army nearly three-million strong. Constantinus beheaded the Imperial Commander and declared that Nova Terra was now free of the Emperor's iron grip.
The Renegade Astartes Sergeant renamed the world Constantinium and under his rule the mob was given free rein. Constantinus plunged his newly conquered world into an anarchic age of darkness as bloodthirsty crowds bayed in the streets and sacrifices were soon made to the Ruinous Powers. Called by their Dark Gods, dozens of Chaos Space Marine warbands travelled to Cirtus to join the Renegades. Constantinus fought the best Champions of Chaos to arrive and defeated them, claiming their warbands for himself. He then embarked on a terrifying pogrom of other planets in the neighbouring star systems, and within a solar decade, the rebel sergeant's megalomania escalated until it plunged the whole sector into open civil war. Eventually Imperial forces, including the Iron Knights Chapter, arrived to reclaim the world for the Imperium, and war raged for thirteen standard years, only ending with the death of Constantinus at the hands of Officio Assassinorum assassins. Even three hundred standard years later, pockets of rebels continued to still hold out in the volcanic plateaus of the world, having made their lair within the labyrinthine lava tunnels found in that region. It was from these hidden cave systems that the rebels continued to carry out guerrilla raids against the Emperor-fearing folk of Nova Terra. It was within those haunted caverns that they continued to make sacrifices to their blasphemous gods in the name of Constantinus the Liberator -- a name that would forever after be a stain upon the reputation of the noble Sons of Guilliman. Eventually, by 981.M41, the Constantinus Iconoclasm had ended and Constantinium was liberated from the Forces of Chaos. The world's name was restored to Nova Terra.
The Fall of Salvation-Gamma
During one notable incident of the conflict that occurred in 981.M41, the Night Reapers Chapter was assigned to defend the Shrine World of Salvation-Gamma. But instead, they forgot their duty for, when confronted by a massive counterattack led by a dozen Chaos warbands drawn to the Iconoclasm's revolt alongside an unknown number of degenerate mutant hordes from the edge-worlds of the sector, the Night Reapers had abandoned the Shrine World as both effectively indefensible and of "negligible strategic worth." Rather than allowing the world to fall, the Night Reapers turned their own weapons on the basilica-cities and granted the pilgrims and refugees who had sought harbour there a "merciful end." The rage of the Ecclesiarchy over this loss was boundless and ensured the Night Reapers Chapter's censure by the High Lords of Terra. Shorn of their Fortress-Monastery and Chapter homeworld, they were condemned to the perilous and thankless task of policing the outer reaches of the Laanah Rifts. The Night Reapers bore their punishment with grim impassivity and obedience but little contrition -- or at least appeared to. Within a solar decade, however, Imperial contact with the Chapter, which had long carried a reputation for ruthless efficiency, independence and technical aptitude, grew untowardly infrequent. Soon, all official contact with the Chapter ceased, their ultimate fate unknown.
Forces of Constantinus
- The Iconoclasts - The Iconoclasts were made up of former Sons of Guilliman Space Marines who willingly followed their former brother Constantinus into damnation, and later served as his personal bodyguards. These fallen Astartes helped shape the former capital world of Nova Terra, and a dozen worlds across the sector like it, into the nightmarish vision of their mad Chaos Lord.
- The Zealous - The Zealous were the masses of so-called "liberated" Nova Terran humans who fought in Constantinus the Liberator's name, and who were charged with the defence of the Chaos Lord's realm. They made the Imperial invaders pay for every metre of ground gained in blood.
- The Enlightened - The Enlightened were those who had witnessed first-hand the fate of those who had challenged Constantinus' domain and chose to side with the Chaos Lord, rising to become his most important and useful servants.
Notable Followers of Constantinus the Liberator
- Maimon and Pius - Former Battle-Brothers of the Sons of Guilliman, and later Constantinus' personal bodyguards called the Iconoclasts. This pair of former Space Marines were the most loyal of all of Constantinus' devotees. They wore corrupted battle-plate that was red-black and gold like their Chaos Lord's, the eight-pointed Star of Chaos raised from the ceramite of their left shoulder pauldron where once was displayed an altogether different insignia.
- Kabiel, "Skull-taker" - A Chaos Space Marine from beyond Nova Terra who had been drawn to Constantinus' rebellion. He later became one of the most faithful servants of Constantinus amongst the ranks of the Enlightened.
- Gha'gur Nor the Slythian - A Chaos Space Marine who once served in the warband of Ghorgoth the Oppressor, who had been drawn to Constantinus' rebellion in the Viridis Sector, and later became known as the Herald of Constantinus, the most faithful of the Enlightened. He wielded the mighty weapon Foe-smiter in battle.
- Codex: Chaos Space Marines (6th Edition), pg. 24
- Codex: Chaos Space Marines (4th Edition), pp. 18-19
- Imperial Armour Volume Thirteen - War Machines of the Lost and the Damned, pg. 25
- Treacheries of the Space Marines (Anthology), "Liberator," by Jonathan Green, pg. 157