The Eisenstein was an Imperial Frigate that served under the authority of the Death Guard Legion of Space Marines during the end of the Great Crusade and the start of the Horus Heresy in the early 31st Millennium.
Before their purge in the first battle of the Horus Heresy, there were still many Space Marines in the Traitor Legions who were loyal to the Emperor, rather than to the Warmaster Horus or their individual Primarchs. Among them were a small cadre of 70 Death Guard Astartes who were led by Battle-Captain Nathaniel Garro of the Death Guard's 7th Great Company.
These warriors, remembered as "The Seventy," escaped during the Battle of Istvaan III in a small Imperial Frigate that was part of the Death Guard's Expeditionary Fleet, the Eisenstein. Their goal was to warn the Emperor of the tragedy that had befallen the Imperium with Horus' betrayal and the start of the great civil war. The vessel did not survive the harrowing journey, but its crew completed their mission.
The Eisenstein was considered an old vessel even during the time of the Horus Heresy. The ship was over 2 kilometres long and resembled a Gladius-class Frigate though its actual class is unknown. By the start of the 31st Millennium the vessel was in service to the Death Guard Legion's fleet, usually for picket duties.
The Eisenstein's ship master explained that the vessel's name meant "iron-stone" in an ancient language of Old Earth and that it had actually been named after two famous men of the Age of Terra. One had been similar in profession to a Remembrancer, and the other had been a scientist.
Battle-Captain Nathaniel Garro of the Death Guard Legion's 7th Great Company greatly distinguished himself when fighting alongside a detachment of the Sisters of Silence in the closing days of the Great Crusade against the xenos known as the Jorgall; their leader, the Sisters of Silence Oblivion Knight Amendera Kendel, promised to present Garro's name to the Regent of Terra, Malcador the Sigillite, in recognition of his dutiful service to the Emperor. Similarly, she spoke well of him to the Death Guard's Primarch Mortarion, who rewarded his Battle-Captain by selecting him for the tradition of sharing his cup aboard the Death Guard flagship Endurance.
Mortarion also chose this moment to subtly sound Garro out about where he and the Astartes of the 7th Great Company might stand if the Primarch chose to join the Warmaster Horus' rebellion against the Emperor of Mankind. Upon learning that Garro was unwilling to join the warrior lodge within the Death Guard, Mortarion decided to take Garro to the meeting with Horus at the initiation of the Istvaan Campaign as his Equerry, in an attempt to ensure Garro's loyalty to what the soon-to-be-Traitor Legions were about to do in that benighted star system.
The 7th Great Company were part of the Astartes task force assigned to secure Isstvan Extremis, the outermost world of the Isstvan System, ahead of the planned massacre of the Loyalist Astartes of the Traitor Legions during the Battle of Istvaan III. During this battle, Garro was badly wounded by the enemy leader who was a Slaaneshi mutant and he lost most of his right leg, necessitating an augmetic replacement once he was back aboard the Death Guard fleet.
Flight of the Eisenstein
The time required for Garro to get used to the cybernetic replacement for his leg meant that he could not be declared fit for combat duty on Istvaan III, where he would surely have been among the Loyalist Astartes caught in Horus' treacherous virus-bombings, so he was instead posted along with his command squad and nearly 100 Astartes of his company to the Death Guard Frigate Eisenstein alongside Captain Ignatius Grulgor of the Death Guard's 2nd Great Company. Gulgor was a member of the Death Guard warrior lodge and of the circle of Death Guard officers willing to follow Mortarion into rebellion alongside Horus against the Emperor.
It came to pass that Garro was in command of the Eisenstein when Captain Saul Tarvitz of the Emperor's Children Legion made his attempt to reach the surface of Istvaan III and warn the Loyalist Astartes there of Horus' impending betrayal. Garro made the crucial decision to allow his honour-brother to reach the surface of Istvaan III and also learned of Horus and his own Primarch Mortarion's plan to rebel against the Emperor, which horrified Garro beyond words.
Once Garro had learned of the betrayal, Captain Grulgor and his small detachment of Traitor Marines attempted to kill the captain and his detachment of Astartes from the 7th Great Company aboard the vessel. Grulgor and his fellow Traitors failed, largely due to the sacrifice of Garro's Legion serf and Equerry, Kaleb Arin. Arin, Grulgor and his fellow Traitors were killed by a gruesome infection by the Life-Eater Virus that escaped from a damaged Virus Bomb that had been secretly loaded aboard the Eisenstein so that the Frigate could join the bombardment of Istvaan III on the orders of Mortarion once Garro and his fellow Loyalists were dead.
Not long after, the Eisenstein took aboard other victims of the betrayal who had fled the Warmaster Horus' own flagship, the Gloriana-class Battleship Vengeful Spirit, including Captain Iacton Qruze of the Sons of Horus' 3rd Company and the Remembrancer-turned-Saint Euphrati Keeler, whose conversations with Garro in the times after the betrayal strengthened his belief in devotion to the Emperor and ignited the flame of his growing faith in the Emperor's divinity.
Determined to flee the Istvaan System for Terra so as to warn the Emperor of Horus' terrible betrayal, the Eisenstein was badly damaged by the massive Death Guard Battleship Terminus Est that was under the command of the Death Guard's First Captain Calas Typhon and barely made the jump into the Warp.
Adrift in the Warp
Once in the Warp, the damaged Eisenstein attracted the attentions of the Chaos God Nurgle, the Plague Lord, who had already claimed the Death Guard Legion as his future champions and had no desire to see Horus' rebellion against the Emperor suffer a setback. Because the Eisenstein 's Gellar Field had been weakened by the damage the starship had sustained during its flight from the Istvaan System, the Dark God was able to snake his malign influence into the vessel from the Warp.
Nurgle's insidious power resurrected Grulgor, his dead Astartes and the ship's crew who had sided with him, creating the first Plague Marines. The ensuing battle between the infected Warp creatures and the Loyalist Death Guard aboard the ship resulted in the death of the vessel's only Navigator.
Grulgor, using a Plague Knife, managed to infect a member of Garro's command squad, the Space Marine Solun Decius, with the terrible daemonic disease known as Nurgle's Rot, and almost triumphed over Garro. However, Garro ordered the Eisenstein to make an emergency transition out of the Warp. Without access to the infernal power of Nurgle sustaining them within the Immaterium, Grulgor and his corrupted brethren were killed, their souls sucked back into the Warp, though Grulgor would later be resurrected once more as a Daemon Prince of the Plague Lord.
Stranded hundreds of light years from any stretch of inhabited space, Garro ordered the Eisenstein 's captain to overload the Frigate's Warp-Drive and then jettison it out into space. Garro hoped that the detonation of the Warp-Drive would produce such a powerful signature in the Immaterium that any passing Imperial starships might be willing to stop and investigate. The plan would also guarantee that if no rescuers appeared, the Eisenstein would never reach another destination and its crew and passengers would die in the black desert of interstellar space.
However, the ensuing explosion of the Warp-Drive echoed across the Warp and acted as a beacon for the Primarch Rogal Dorn and the fleet of his Imperial Fists Legion, who had been becalmed by Warp Storms unleashed by the gathering power of the Dark Gods as the Heresy unfolded on their way back to Terra on the order of the Emperor. Dorn rescued Garro and his men, then scuttled the severely crippled Eisentein.
Dorn proceeded to take the Eisenstein 's survivors to Luna aboard the great mobile fortress-monastery Phalanx. While initially reluctant to the point of outraged violence to believe Garro about his brother Horus and the other Primarchs' betrayal of the Emperor, once faced with overwhelming evidence from multiple sources, including the testimony of a member of Horus' own Luna Wolves Legion, he eventually relented and the Navigators of Dorn's massive fortress ship made their way to the Sol System where Dorn would inform his father the Emperor of this dreadful news.
After arriving in the Sol System, Captain Garro, his fellow Death Guard Astartes, Euphrati Keeler, and Iacton Qruze were all placed in the Somnus Citadel, a fortress on Luna that belonged to the Sisters of Silence while the Emperor determined whether they were truthful or were further pawns of the Chaos Gods. Even upon reaching Luna, and with the news of the betrayal delivered, Garro's trials were still not over, as one of his Astartes, Solun Decius, had become infected with Nurgle's Rot on board the Eisenstein.
Wracked by constant pain, Solun finally gave in to the temptations of Nurgle to ease his suffering and allowed his corrupted body to be possessed and mutated by a Nurglite daemon known as the Lord of the Flies. His body was twisted by the possessing entity into a hideous daemonic form. In this state Solun killed the two Astartes who had been conducting the death vigil over his prone form. The Lord of Flies went on a killing rampage throughout the keep. Garro was forced to battle Decius throughout the Sister of Silence's citadel and out onto the barren, airless surface of Luna itself. He eventually bested the daemon who had once been his trusted comrade and banished the hideous entity back to the Warp.
Afterwards, Garro, Qruze and the Sister of Silence Amendera Kendel were approached by Malcador the Sigillite, the Regent of Terra, and told that the Emperor needed them to form a new Imperial organisation, beyond the boundaries of the existing Imperial bureaucracy, which would utilise "men and women of inquisitive nature, hunters who might seek the witch, the traitor, the mutant, the xenos".
Under the Sigillite's own seal, Garro was tasked with finding 7 other Astartes from among both the Loyalist and Traitor Legions who were utterly devoted to the Emperor and his Imperium in body and soul. These Space Marines would become the Knights-Errant, the core of what would later become the Grey Knights Chapter of Astartes, the Chamber Militant of the Inquisition's Ordo Malleus. The Inquisition had been born in the fires of betrayal and heroism.
Dark Imperium Era
In the centuries since the end of the Horus Heresy, the Eisenstein has garnered a mysterious reputation and its current status -- whether it was truly destroyed or not -- remains unclear.
Sometime after the formation of the Great Rift, many saw the vessel reappearing on multiple occasions. When the ghost vessel appears for the seventh such time, it is said that Mortarion himself will appear and wreak destruction.
- The Flight of the Eisenstein (Novel) by James Swallow
- Codex Heretic Astartes - Death Guard (8th Edition), pg. 22
- Realm of Chaos - Slaves to Darkness, pg. 240
- Space Marine (Board Game) 1989 Edition Rulebook, pg. 7
- Garro: Sword of Truth (Audio Book) by James Swallow