The Brotherhood was a Genestealer Cult linked to Hive Fleet Kraken that rose up on the Imperial Hive World of Ichar IV in the days just before the start of the Second Tyrannic War in 992.M41. Their rising was the precursor to the Kraken's arrival in Imperial space. The Brotherhood initially presented itself as a variant of the Imperial Cult that preached that the return of the Emperor in physical form was imminent.
The Brotherhood's rebellion was ultimately defeated by the intervention of Inquisitor Agmar of the Ordo Xenos and the Ultramarines Chapter under the command of their Chapter Master, Marneus Calgar. Later, as Hive Fleet Kraken swept through the same region of space, it would be discovered that some elements of the cult had survived and would aid the Tyranids during their own assault on the planet.
Eventually, with the combined support of the Ultramarines, Ichar IV's Planetary Defence Forces and the Astra Militarum, the Inquisition successfully destroyed the invasion and cleansed the planet of all remaining Genestealers and Tyranid bioforms.
One of the Astra Militarum units involved in the fighting on Ichar IV was the 13th Penal Legion, the so-called "Last Chancers." The 13th Penal Legion fought the Tyranids on Ichar IV and the bitter fighting resulted in terrible casualties for the Legion.
Ichar IV Rebellion
Before the true threat of Hive Fleet Kraken revealed itself, the Imperium had first faced uprisings on its Eastern Fringe that served as the prelude to the main Tyranid threat. One such rebellion occurred on a Hive World named Ichar IV. Ichar IV was vital to the operation of the Eastern Fringe as its huge manufactoria formed the centre and lynch pin of one of the few densely populated Imperial sectors in the widespread Ultima Segmentum.
The entire planet had been seized from the control of the Imperium by a religious fundamentalist group named the Brotherhood. Years before, the Brotherhood had captured the hearts and minds of the population of the planet by preaching the return of the Emperor in physical form and promising better times to come. This is the sort of promise that was sought by the workers of the Icharran manufactoria because they lived lives with no power, hope of betterment or freedom. The Brotherhood quickly set up missions and chapels throughout the poor regions of the planet.
The Ecclesiarchy closely monitored the Brotherhood for any signs of corruption or heresy, but none could be found. Eventually, permission was sought and granted for the construction of a Brotherhood cathedral in Lomas, the biggest city on Ichar IV. Shortly after the completion of the Brotherhood's cathedral the trouble began; the Brotherhood refused to pay its tithes to the Planetary Governor and would not allow its members to be inducted into Ichar IV's Planetary Defence Force.
Brotherhood Preachers whipped the Icharran population into a frenzy, prophesying that the Emperor would return in the flesh soon. Brotherhood militias began to roam the streets, punishing anyone they deemed to be "unbelievers" rather than actual criminals.
Events accelerated when rioting broke out during a mass demonstration outside of the great cathedral in Lomas. Arbitrators of the Adeptus Arbites moved in with Power Mauls and Suppression Shields to put down the rioters forcefully, but were fired upon from the cathedral by Brotherhood militia. The Arbitrators returned fire and killed several of the Brotherhood's militia members.
This only enraged the mob further and they surged forwards several times, eventually forcing the Arbitrators to fall back, especially as another, larger mob had just arrived to support them. Rioting then spread across the planet and most of the forces of the Arbites were forced back. When the Planetary Defence Force was called in to restore order, most members of the force rebelled and joined the ranks of the Brotherhood.
Eventually, news of the assassination of the Planetary Governor reached the public and vicious fighting broke out in all of the hive cities of the planet. Within solar hours, tanks decorated with the revolutionary banners of the Brotherhood were seen driving down roads in cities, pushing the Arbites back.
With the dawn, news of the assassination of the Imperial governor and most of his ministers had spread over the entire planet, and the Brotherhood quickly seized control of several broadcasting stations, announcing the establishment of their new theocratic state in the name of the returning God-Emperor.
The Arbites still held control of the majority of the Icharran countryside and the Arbites precinct-fortress that guarded the centre of Lomas. Most of the cities had been captured by the Brotherhood, denying the Arbites vital resources. Inquisitor Agmar of the Ordo Xenos arrived twenty-seven solar days after the rebellion began, on the same day that the Arbites fortress in Lomas was overrun by Brotherhood forces. Most of the Judges in the fortress escaped, moving to take control of the four main power stations of the city.
Inquisitor Agmar saw this as much more of an organised rebellion than a sporadic outburst of popular religious feeling. He called for the support of the Ultramarines Chapter of Astartes to help the forces of the Imperium retake the planet. While the remaining Imperial forces waited for the arrival of the Ultramarines, they bombarded the rebel cities and pushed back vicious assaults by Brotherhood militia battalions. Repeated attempts to reach the power stations of Lomas failed and, six days after Agmar arrived, the Arbites detonated several Melta Bombs, completely destroying the generators.
Now the war transformed into a long, grinding campaign of urban combat with casualties spiraling upwards daily. Every doorway could possess a booby trap and there were Brotherhood snipers in place all over the Renegade-held cities. Entire Astra Militarum patrols that remained loyal to the Imperium disappeared without trace in the chaotic maelstrom. The rebellion promised to be a long one as the Brotherhood held the armouries of the Imperial Guard regiments assigned to the planet and had the support of the majority of the Icharran population to draw on to become soldiers in its militia.
Inquisitor Agmar led several small forces of Imperial Guardsmen and Arbitrators into Lomas to uncover the true nature of the Brotherhood. He was slowly piecing together the story when, in a chance raid, he slew a Neophyte Hybrid of the Brotherhood and saw what manner of xenos creature was actually leading the revolt -- foul Tyranid Genestealers! The Brotherhood was, in fact, a Genestealer Cult! Agmar sent an astropathic message confirming his fears of another Tyranid invasion to the Inquisition and awaited the arrival of the Ultramarines.
The Genestealer Infestation
Thirty-nine solar days after the Icharran rebellion began, the Ultramarines' Battle Barge Octavius entered orbit above Ichar IV and deployed its Drop Pods. The planetary defences were largely inactive due to the damage to the power generators of Lomas and as such the Space Marines' landing casualties were light. The Space Marines secured the Astra Militarum's armouries and the Imperial Governor's palace and fought off several poorly organised counterattacks, causing massive casualties among the Brotherhood's forces. Outside, the remaining Imperial Guard forces launched coordinated attacks to link up with the Ultramarines, using their Leman Russ main battle tanks as moving strongpoints and slowly, inevitably, the Brotherhood's lines bent back.
More than 20 Veteran Marines in Terminator Armour from the Ultramarines' elite 1st Company teleported into the great Brotherhood cathedral in Lomas and destroyed the cathedral's defenders after Agmar sent a message to the Octavius via spy satellite. More guards appeared from side doors and a storm of lasbeams and autoshells ripped out, massacring many of the Brotherhood guards, but not before several of the Terminators were dragged down. The Terminators' single Heavy Flamer proved to be invaluable, its flames incinerating the unprotected assaulting forces. Yet some of the Brotherhood Neophytes were striking out with inhuman speed and terrible claws, indicating their xenos heritage.
The Terminators then spread out and searched for the myriad of secret passages that they presumed existed beneath the Brotherhood cathedral. They soon found one under the altar, and the altar was quickly removed. As they moved down into the crypt, they heard the clattering of claws on stone. As the creatures jumped into the lights of the Ultramarines, they were identified as Genestealers.
This showed the Inquisitor's belief that there was a Genestealer Cult at the heart of the Brotherhood's revolution to be correct. The battle began and raged for a long time. Hundreds of Genestealers died, piling up one on top of each other. Eventually, the horde's numbers were spent in their attack. Several Ultramarine Terminators had been killed as their armour was torn open by the inhumanly sharp claws of the Genestealers. The remainder of the Astartes moved further into the crypt without encountering more of the creatures.
Deep beneath the city of Lomas they found a huge cavern where the huge and bloated great grandfather of the brood, the powerful Genestealer Patriarch, sat. As the Terminators approached, another horde of Genestealers intent on protecting the alien master attacked the Terminators from out of nowhere. Storm Bolters rang out, resulting in pure carnage.
The company Librarian fought his way to the dais but the Patriarch used its psychic powers to attack the Space Marine psyker. A surge from the Astartes' psychic hood broke the spell and the Librarian forced his body out of the real world for an instant and then he reappeared, teleported onto the dais. The creature lashed out and blood and sparks flew from the Librarian, but the Patriarch easily parried the return blow.
The Librarian called on his Battle-Brothers for assistance and the dais was swept with Bolter fire. Some shells pierced the Power Armour of the Librarian but the Patriarch was also wounded. The Librarian used this opportunity to strike with his Force Axe, the Librarian's own psychic power behind the blow allowing the weapon to tear through the tough hide of the Patriarch.
The Patriarch was dead, suddenly leaving the brood and the entire revolution leaderless and unconnected by the cult's Broodmind. The revolution felt the death of its leader and lost its impetus and cohesion. The remaining Terminators slew the rest of the Genestealers and the battles above slowly stopped as the revolutionaries could only retrench themselves and no longer act in a fully coordinated manner without the Patriarch's subtle psychic guidance over the cult. Small groups of Brotherhood Acolyte Hybrids and Neophyte Hybrids held their positions in bunkers and towers but were soon destroyed by the tanks and heavy fighting vehicles of the Astra Militarum.
Ichar IV was back under the control of the Imperium and all remnants of the Genestealer Cult - the Genestealers, their hybrids, infected humans, cult members and traitors -- were ruthlessly wiped out. Inquisitor Agmar, leading the Ultramarines, methodically purged the planet, which eventually returned to normal.
There were still questions that remained unanswered. One was the fate of the human leader of the Brotherhood, as his body was never found. The second was that the planet's Astropaths had reported a shift in the Warp, distant still, but the oldest of the Astropaths had sensed the psychic call of the Genestealer Patriarch radiating out into space and felt the change in the Warp. He had sensed something vast and shadowy, a monstrous entity which had turned its attention towards Ichar IV -- Hive Fleet Kraken.
Battle of Ichar IV
Fortunately for humanity, Hive Fleet Kraken did not remain divided into separate tendrils indefinitely and eventually began to coalesce into a single, massive swarm on Ichar IV, the Hive World whose large Genestealer infestation had been the initial harbinger of the Kraken's arrival in the Milky Way Galaxy. As the Tyranids approached the planet, thousands of Genestealers and hybrids of The Brotherhood suddenly burst from the underhives in support of the invading xenos, giving the lie to claims that the infestation had been entirely purged years earlier.
Defence perimeters were completely overrun, Imperial Guardsmen slain by the thousands. In the terrible confusion, an ever larger number of Tyranid organisms made planetfall -- not only the Termagants and Gargoyles that had composed the vanguard of the prior assaults, but the truly monstrous Carnifexes and Tyrannofexes as well. Worse still, gigantic Hierodule and Hierophant Bio-Titans stalked across the surface of the beleaguered world. The Tyranids had unleashed on Ichar IV every terrible organic weapon in their arsenal.
Despite all this, Ichar IV was not yet lost to humanity. Forewarned of Tyranid interest in the world by the previous Genestealer Cult infestation, the Imperium was able to mount a more solid defence in the Ichar System than in the other areas of the Eastern Fringes under assault by Hive Fleet Kraken.
Chapter Master Marneus Calgar, the Lord of Ultramar and hero of the First Tyrannic War, led the Ultramarines into battle against their old foe on Ichar IV just as he had against Hive Fleet Behemoth on Macragge 200 Terran years earlier. The Ultramarines inflicted crushing losses on the Tyranid armada in space above the planet and in the claustrophobic corridors of the towering Icharran hive cities.
Space Marine Tyrannic War Veterans of the First Tyrannic War made planetfall and scoured Ichar IV's hives in a series of close-quarter battles that lasted for close to a full Terran year. By employing the same tactics that had proved successful in defeating Hive Fleet Behemoth in Ultramar two centuries earlier, Marneus Calgar rallied the Imperial defenders of Ichar IV and cast the Tyranids from that planet forevermore. But as always, victory against the Tyranids had come at a terrible price -- Ichar IV was reduced to a smoking charnel house of death and destruction, a world and its people sacrificed so that the Imperium of Man might endure yet another storm.
- Codex: Tyranids (8th Edition), pg. 22
- Codex: Tyranids (5th Edition), pp. 23-25
- Codex: Tyranids (3rd Edition), pg. 48, inside back cover
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