Thirty nine days after the outbreak of rebellion the Ultramarines battle barge Octavius entered Ichar's orbit and prepared to deploy its drop pods. Ichar IV's defences were still largely ineffective because of the damage inflicted on Lomas' s Generatorium by the Arbites and drop casualties were light. Companies of Space Marines seized the main defense armories and the governor's palace where the Brotherhood militia headquarters had been established. At first the Brotherhood was taken by complete surprise and the primary objectives were quickly secured. The Brotherhood militia launched a series of desperate counter attacks to dislodge the Space Marines but their forces were critically disorganized by the destruction of their HQ and they were beaten off with heavy losses.

Outside the city the Imperial Guard launched a major assault to link up with the Ultramarines. Fire and smoke leapt into the sky as artillery shells burst upon the city. Laser fire slashed back and forth as crouched figures scrambled from cover to cover. Heavy bolters flared through the murk, their shells kicking up erupting lines of dirt and rubble. The Imperial Guard doggedly advanced using their Leman Russ tanks as moving strongpoints and the Brotherhood's lines bent back before them.

At the height of the attack Inquisitor Agmar's specially-placed spy satellite picked up militia forces leaving the Brotherhood cathedral and moving up to contain the Imperial assault. The Inquisitor knew the time had now come when one hold stroke would end the rebellion. He sent a prearranged signal to the Octavius orbiting high above.

In the echoing nave of the cathedral a crackling blue haze appeared, brightened and then in a flash of azure light solidified into a number of hulking figures. The Brotherhood guards at the doors wheeled round in time to be ripped apart by a thunderous hail of explosive shells. More than twenty Space Marines in Terminator armour stood towering over their torn corpses in the sudden silence that followed. More guards, Neophytes and Acolytes suddenly poured into the cathedral through side doors as the Ultramarines Terminators spread out from their teleport point. A storm of lasbeams and autoshells rattled off the Terminators' thick armour plates to no avail: storm bolters were raised in gauntleted fists and the walls were painted with Brotherhood blood.

A handful of survivors hurled themselves into close combat with the giant warriors. Voluminous robes fell hack to reveal bone-ridged heads and glaring eyes when the Neophytes lashed out with their inhuman claws. Some of the Terminators were overwhelmed and dragged down by the supernatural ferocity of the mob but the roaring jet of a heavy flamer cut across the survivors before they could exploit their victory. Smoke and the stink of burned flesh billowed up to the high-arched roof from the funeral pyre.

The Terminators spread out with machine-like precision, some froze into overwatch positions while the others searched the cathedral for the hidden passages they knew it must contain. Their Librarian pointed to the altar and more explosive shells blasted it apart, revealing steps down into darkness.

Flipping on their suit lights the Terminators filed down the steps to find the black heart of the Brotherhood. A dismal crypt lay below, with many twisting passages spreading out from it in all directions hut the Librarian could sense the way through the labyrinth. The Terminators' scanners came to life as they left the crypt, showing multiple foes closing quickly on their location, creatures that moved too quickly to be human. The Terminators moved to the positions they would cover from overwatch and waited, ready to deal death at the slightest movement.

First came the distant clicking of claws on stone, then the thunder of the creatures' armoured bodies striking the walls and each other as they rushed forth to bring swift death to the intruders. The first of them sprang into the glare of the lights, its four deadly arms held high over its crouched body and bestial head. Genestealers! No doubt was left now, the Inquisitor was right: a viper's nest of aliens lay at the heart of the rebellion. Fangs and claws glittered as the Genestealers ran forward with insect-quickness to slay their hated foes. Storm bolters roared, sounding impossibly loud in the confined tunnels, explosive tipped bolts caromed from chitinous bodies or pierced them and blasted alien flesh to bloody pulp. The cleansing fires of flamers incinerated whole tunnels at a time but the creatures charged forward without fear or hesitation.

Each strobing flash of the storm bolters showed the foe getting closer. They swept over the bodies piled in front of the Ultramarines and tore into the Terminators. Three of the armoured giants were ripped apart in as many seconds before the rest fell back to the crypt. The Genestealers leapt after them without pause, easily catching the rearguards as they backed away still blasting. Who can say how many more of the aliens were blown apart or crushed by the Terminators' power fists before they were overrun? Not enough to stop the onrushing brood but enough to slow them while their brethren prepared to fight again. In the crypt flamers held side passages against flanking Genestealers and forced them to pour forth from one end of the room. The combined fire of a half-dozen storm bolters burst through the horde and, as the survivors leapt into cover behind great stone sarcophagi, the Librarian summoned a purifying column of warp fire. Unnatural flames filled the end of the crypt, hissing fires that ate through alien flesh as though it were fat and gristle instead of iron hard chitin and steely cartilage. Most of the brood burned in an instant, the rest fell to the explosive bolts which raged through their ranks like a miniature artillery barrage.

The Terminators moved on, cautiously now because they were few. No more of the nightmarish Genestealers barred their way or leapt from ambush as the Ultramarines pushed ever deeper into the heart of darkness. Deep beneath the city they found what they were seeking in a high-groined chamber with carved walls like the ribs of some great beast. There the Genestealer Patriarch crouched on a great dais, huge and bloated with the power of its sprawling brood. It squatted with arms outstretched, head turned upward as if listening for some distant call as the Ultramarines marched into the hall. They raised their weapons to destroy the abomination and it lowered its eyes to gaze on them with a threatening hiss.

Without warning a horde of monstrosities poured into the chamber from between the calcified ribs-walls. Three-armed hybrids, tainted humans and purestrain Genestealers leapt forward to protect their all-father. A wall of explosive bolts marched along the mob and the chamber dissolved into a scene of chaos and bloodshed as the howling fanatics hurled themselves on the Terminators. The Ultramarines Librarian cut his way forward through the creatures, the glowing white blade of his force axe leaving a trail of shorn limbs and lopped heads behind him. Each step became harder, as if he were wading through deeper and deeper water. He could feel the palpable psychic waves of alien thoughts beating against his mind as the Patriarch exerted its ancient, implacable will upon him. Deep pits opened in his subconscious, ready to swallow his psyche whole.

A shocking surge from the Librarian's psychic hood broke the spell. Focusing his own indomitable will, the Librarian forced his body out of the physical world for an instant, and in an instant he was gone. A bright flash marked his departure, another flared at his point of arrival as he teleported onto the dais with the Patriarch. The creature span round and lashed out its claws with incredible speed. Blood and sparks flew from the Librarian's armour as the claws ripped into it. The Patriarch easily ducked away from his clumsy backswing. The beast pounced again and rained a flurry of blows on the armoured figure which were almost too swift to follow.

In desperation the Librarian called to his battle brothers and the dais was swept by storm bolters. Indiscriminate fire ricocheted off the Librarian's armour but some shots struck and wounded the Patriarch. In its moment of distraction the Librarian swung his force axe in an irresistible arc which carved through the Patriarch's armoured hide with a flash of power. The force axe rose and fell, hacking the Patriarch into a bloody pulp and spraying purple ichor across the chamber.

With the death of its Patriarch the brood was thrown into confusion. In the chamber the handful of remaining Terminators slaughtered the mass of creatures assailing them. Nothing escaped the blasts of their storm bolters and the cleansing fires of their flamers as the Terminators exacted some small measure of revenge for the death of their forebears over two centuries before. In the city above the Brotherhood units resisting the Imperial Guard offensive collapsed. Small knots of fanatical Acolytes and Neophytes held out in towers and bunkers but triumphant Imperial Guard tanks swept through the rubble-strewn streets crushing all opposition.

Ichar IV was back under the iron heel of the Imperium within three weeks. All signs of the Genestealer infestation were thoroughly rooted out by the energetic Inquisitor Agmar with the assistance of the Ultramarines. Yet at the end of the campaign several mysteries remained unanswered. The first was what had become of the Magus, the human-seeming leader of the Brotherhood who had disappeared at the start of the rebellion. His body was never found and no prisoners were able to shed light on his whereabouts, even under Agmar's most persuasive questioning.

The second mystery was the reports of Astropaths and the Ultramarines Librarian who had slain the Patriarch. They told of sensing a faint psychic disturbance like a long, keening call or a signal radiating from the planet, a signal which had been cut off when the Patriarch was killed. The oldest and most powerful of the Astropaths had told the Inquisitor that he too had sensed the Patriarch's call and that he had felt a distant shift in the warp. It was a sense of something vast and seething, a shadow of a monstrously powerful entity which had turned its attention to Ichar.

When Agmar submitted his report to the conclave of the Inquisition he was warned of a growing number of reports from survivors fleeing from the outer fringes. The information was garbled and contradictory but one fact stood out, the Tyranids had returned with a new hive fleet, Hive Fleet Kraken.