The Battle for Nenia Pomarium - or more accurately the battle to hold Port 624, was a battle fought in late M41. The Space Marines of the Revenants Chapter's Fourth Company - were sent to the planet Nenia Pomarium to investigate the possibility of a Genestealer infiltration. By the time they get there, the Tyranid force known only as the Alpanga Swarm had already arrived, necessitating a last ditch holding action to pull the untainted survivors out.
Revenants Fourth Company
The Revenants Fourth Company, under the command of Jared Severus, were on a mission to locate the unknown Space Marine who had aided the Revenants Chapter Master against Hans Nieman and Sanctimonia Praesentia, when they received a distress call from the planet Nenia Pomarium. The planet had recently been forced to deal with an attempted Xeno incursion by Genestealers and, though the creatures had been apparently defeated, the authorities required the aid of those more experienced with the Tyranid taint to be certain. Knowing his first duty was to the peoples of the Imperium, Captain Severus agreed.
When the Revenants arrived however, they found things in a bad way; the Tyranids were nearly upon the planet, and with precious little time to organise an effective defence, the best Severus could do - as much as it galled him - was to order a retreat, and an evacuation.
The Planetary Government was admirably speedy in organising the retreat, with over half the population hang already been evacuated. The remaining population were about half way through evacuation when the Tyranids hit. The majority of the spaceports - and their people - fell within hours, while more managed to escape. Eventually, the only port that needed holding was port 624; a not very easily accessed port, but accessible enough for the mission. The colonists would take time to be herded informs last evac ships, and now only 85th platoon PDF under Major Lewis Mortenson and Captain Severus' Marines were left to hold the last defences against the Tyranids.
Apart from the small, scantly armed platoon of Guardsmen, the Space Marines had less than a full company left to hold against the Tyranid horde, supported by a single squad of Terminator armoured Veterans. However, there was a strange light at the end of the tunnel for the Marines, for at the darkest hour of that battle, when all hope seemed lost to them, the Space Marine they had been seeking, known as the stranger of Orbis, appeared. Captain Severus acknowledged the reports of his quarry's arrival with little but a nod, and the stranger stood with his brothers.
The Tyranid's of the Alpanga swarm are one of those where little is known about their capabilities or their organisation; it is not even known if they are a separate hive fleet. It is known that they have a large number of Genestealers in their forces.
Port 624 was an old fortress with a tunnel leading to the main escape ship. The fortress gates were held by Guardsmen; Major Mortenson refused to countenance wasting Marines on what was likely a suicide posting. Captain Severus held his forces - including the revered Dreadnought "Bob" Robaro - within the Fortress, ready to die to defend the populous of Nenia Pomarium.
Near the fortress was a hele-pad where the last few escape craft had managed to arrive. Devestator Sergeant Andron volunteered to lead the two Devestator squads in an attempt to hold a firing position. Though Severus was loath to allow his brothers to commit suicide in such a manner, he knew such a manoeuvre would be invaluable.
Chaplain Marcus, the Chaplain of the Fourth Company, decided that his place was with those whose faith needed bolstering; he stood with those by the gates, speaking litanies of faith to the Emperor.
The prayers seemed to work: the Tyranid's first bio-plasma barrages seemed to fail. Chaplain Marcus continued yelling prayers to the Emperor, as the Guard targeted the Zoanthropes and destroyed several. The Zoanthropes seemed to be a great threat, but then the only Assault Squad the Fourth had at this point managed to launch a successful assault, destroying them. A cheer went up from the Guard line, but quickly silenced when Tyranid Bio Plasma destroyed the gate, and the Tyranids advanced.
The charge of the Gaunt hordes swarmed over the gates, killing many guardsmen and cutting Chaplain Marcus off. When it seemed the Chaplain would fall however, the Stranger of Orbis appeared, gunning down several Gaunts and pushing the Chaplain away, right before being swarmed by Gaunts. He was not seen again in this battle, and presumed by Severus to have been killed. The Gaunts swarmed further into the fortress, killing many Guard and attacking the Terminator squad, who prepared to sell their lives dearly; all but their sergeant, (a warrior named Meridius) were dragged under in moments, but the Sergeant managed to slay several before being killed himself.
The Devestator squads managed to fire of several barrages which, in conjunction with a Guard unit on the wall, destroyed a Carnifex. However, soon they were overwhelmed by a horde of Genestealers, selling their lives dearly.
Eventually, Severus realised their forces could not hold out any longer against the Tyranid's; a Hive Tyrant advanced over the wall, killing many Guard, while Genestealers swarmed the walls, killing Marine and Guardsman alike, leaving Major Mortenson to hold out alone; he refused to retreat, and told Severus to retreat. Though it galled Severus, he ordered his few surviving troops to withdraw, while Dreadnought Robaro held his ground against the Hive Tyrant; he was utterly destroyed by the creature, but wounded it grievously.
Severus and twenty five other Marines, including Chaplain Marcus, escaped. Mortenson was killed by a Xeno-infected Guardsman, but not before ordering a demo servitor to self detonate, destroying much of the fortress.
The civilian ships escaped, barely, though they had to flee before all the remaining civilians could be evacuated. Chapter Master Flynn contacted Severus and ordered him to return to Peace; the Stranger's apparent death had ended their mission in failure.
The Stranger's Fate
Severus spoke to Marcus about the apparent death of the Stranger; what was strange was, they had been on their way to an apparent sighting of the Stranger on a totally different world weeks away; there was no way the man could have gotten to Nenia Pomarium in time. Marcus told Severus one thing he knew for certain; the Stranger was not the late Marius Tron, as some had postulated; the voice was different. Neither man knew who the Stranger could be, but eventually Severus concluded: "a friend of our Chapter."