Paladins of Thunder

The Paladins of Thunder are a Codex-semi complying chapter from the Ultima Founding born from the gene-seed of the loyalist Primarch Rogal Dorn of the Imperial Fists. This chapter gain some notoriety during the Indomitus Crusade helping their brothers, the Crimson Fists in their darkest hour alongside them against the daemon incursion of the Daemon Prince Rhaxor and, later, helped a Salamanders successor chpter; the Drake Bloods in the desert world of Nimrod.

Thanks to their services, the Lord Regent of the Imperium, Robute Guilliman, conceded to the Paladins of Thunder their homeworld, the agri-world of Zehpyron IV, as well as recruitment rights to the entire Zephyron system.

One of the peculiarities of the chapter is that most of their high ranking officials are members of the Apothecarion of the chapter. This is particularly notable with the title that the leader of the chapter bears: Magister Medicae.

Like most of Dorn's Sons, the Paladins of Thunder revere the Emperor of Mankind, but not like their most zealous brothers, the Black Templars. The Paladins of Thunder think of the Emperor of Mankind as their Grandfather, capable of watching over each one of their grandsons from his Golden Throne. However, think that Rogal Dorn, their Father, is the true embodiment of the Emperors virtues and that he waits beside him and that he will come back once his sons are in the direst of situations.

Indomitus Crusade
In the vaults of Archmagos Dominus Belisarius Cawl, the vats that will house the warriors of the Paladins of Thunder started to be filled with warriors from not only Holy Terra herself, but with some of the bravest men of the Solar Auxilia: their medical officers. This young (and probably scared) men went around the streets and buildings from Segmentum Solar during the darkest days of the Horus Heresy trying to find survivors from not only their fellow soldiers, but from the Angels of Death themselves; knowing that, for every life lost within the forces loyal to the Emperor, they are probably closer to losing against the traitors.

When the Ultima Founding happened in 999.M41, the thousand marines woke under the Red Planet and were claded in white and purpure armor. Damian Talassar, once a medical officer from the Solar Auxilia, was chosen for leading his chapter; not as a Chapter Master, but as Magister Medicae.

They accompanied the other Primaris during the Indomitus Crusade and, maybe because of their geneseed or because of the situation of the planet, the Paladins of Thunder fought alongside the surviving Crimson Fists and their Primaris reinforcements in Rynn's World; killing foul daemons of chaos and saving both human and astartes lives. During this part of the crusade, Magister Medicae Talassar died saving a Lieutenant and a couple of Crimson Fists marines from the blow of a daemon of Khorne, as he used both his narthecium and his plasma pistol to break the gargantuan axe; as his iron halo broke during a previous fight.

Due to his sacrifice, Pedro Kantor, once the battle was over, promised the new leader of the chapter; Aemilius Castor, that the Crimson Fists will be with their brothers in their time of need as well as they did.

Later that century, the Paladins of Thunder fought alongside the Salamanders successor chapter, the Drake Bloods in the world of Nimrod against a massive Ork force that overwhelmed the local hiveworld's PDF and was  in the brink to becoming a WAAAGH!. During this planetary campaign, the recently named Lord Medicae showed his skills as a tactician when he fortified a pass that lead to one of the biggest oasis in the southern continent and were the remains of the PDF were holding positions and then proceeded to crushone of the warboss'  most trusted nob's forces in a battle that will be called "The Green Wall". At the end of the campaign, the skull of the warboss was gifted to Castor as a gesture of good will from the Drake Bloods.

But not only were notable their assitance to fellow Astartes. On the world of Vyrian II, the Paladins of Thunder 3rd Company helped defend alongside the local PDF one of the bases of operations of the Order of Serenity, from the Orders Hospitallers of the Adepta Sororitas against a Tyranid remnant hive and saving their Cannonness from the claws of a Lictor and, with that, a relation of cooperation began between both of them.

After many other battles were the Paladins of Thunder mainly took a support role both as defenders and medical support alongside sisters from the aforementioned order; the Primarch of the Ultramarines gave the Paladins of Thunder the fief of Zephyron IV, an agri-world located in the Imperium's Ultima Segmentum as well as the right to recruit from the other inhabited planet of the system; Zephyron III, a Knight World lead by House Alexios.

Chaos at the doorstep
Once their Fortress-Monastery, the Halls of Solace, was built and Aemilus Castor was anointed Governor of Zephyron IV, the Paladins of Thunder began the usual activities that every chapter inside the Imperium Nihilus does; sending forces to invaded worlds and stop incursions from xenos races across the sector; the Paladins of Thunder did their duty without hesitation, fighting mostly Orks and Traitor Astartes. But,  one day, traitor forces staged a rebellion in Zephyron III and,  few days afterwards, a Chaos fleet of the Alpha Legion descended upon the system with only the 5th and 9th companies located in the system at the moment, alongside Aemilus Castor.

Trying to stop the system from falling to disarray, Magister Medicae Castor sent the 5th Company to Zephyron III to help House Alexios and its retainers against the Traitor Knights and cultists that were reinforced by the Alpha Legion, meanwhile, he'll fortify the capital of his chapter's homeworld, as well as use the small battlegroup as means to both evacuate civilians and to send messages to other Imperial forces nearby.

With help from the 112th Zephyrean Armoured Division and the 71st Zephyrean Regiment, Castor managed to evacuate a half of the population of Zephyron IV before the first wave of Chaos forces attacked.

Once it happened, both the capital and the Halls of Solace were sieged, stopping the forces located in those places to assist one another or other places in the planet, leaving some minor settlements and spaceports defended by the PDF or, in the worst case, at the mercy of the Alpha Legion. With this maneuver, the traitor forces also managed to stop communications between both worlds.

Deeds of Honor
Nevertheless, the stalwart resistance from the Imperial forces managed to survive at least until the arrival of reinforcements spearheaded by the cruiser Valiant Night, that housed the 1st Company of the Paladins of Thunder; as well as several strike vessels from the Crimson Fists' 2nd and 4th Company.

Thanks to the valiant sacrifice of the last remains of the 71st, Castor was able to send a quick transmission to the fleet: "We can hold. ". Unable to receive a response,  he hoped that the reinforcements will follow his orders and help the other planet or, at least, purge it.

This decision came with a cost, however; the Fortress-Monastery fell but not before being set ablaze by the last Tecnomarine of the 9th Company as a squad lead by the Lieutenant Gabriel Javus escaped with the few relics of the chapter, losing all the gene-vats.

Once reunited with the Magister Medicae and the survivors of the Imperial forces on the capital, they were ready to fight to the last man but luckily, there was no need for a heroic sacrifice this time.

From the sky, Imperial Knights and drop pods fell, giving a chance to the defenders to sally forth and make a pincer movement and killing the traitor leader in a swift blow performed by the 1st Company; leaving The Hydra without heads. After this, the traitor forces on the planet were systematically eliminated, as well as a part of their fleet before they retreated to the Warp.

At the end, Castor was contacted by the captain of the 2nd Company of the Crimson Fists, who gave him a heavily modified crimson Power Fist, Kantor's Promise as a gesture of a greater brotherhood between both chapters.

Without Fortress-Monastery and needing both of the inhabited worlds help rebuilding and dealing with surviving cults; the entire chapter was called back to build the new Fortress-Monastery; the Hand of Retribution atop the ruins of the old one; but also to get their mature progenoid glands extracted so the new gene-vats were ready in case new recruits were needed.

Once the inhabitants of Zephyron IV were reunited, they, as well as the remaining houses of the Questor Imperialis of Zephyron III gathered and declared the chapter as "Saviors of Zephyron" and their commander as "Lord Guardian of Zephyron". Thanks to their good relation with the Order of Serenity of the Adepta Sororitas, they were able to stablish a hospital near the system capital, Orfeus, that was decimated by the Alpha Legion during the conflict.

As both the 5th and 9th companies were almost destroyed during the sieges, they were assigned the roles of trainers for the new generation of marines needed. Due to the actions during the campaign, Gabriel Javus was ascended to Captain of the 9th company.

Traditions

 * The Weeping Vigil: During the anniversary of the defeat of the Archtraitor Horus Lupercal, the entire chapter stays still and awake and try to canalize the feelings that their Primarch had when he discovered the lifeless body of his brother Sanguinius  and his father in the brink of death and start to cry tears of sorrow as images that some say come directly from the living mind of the primarch appear directly onto their minds.
 * Champion of the Emperor: As some of their chapter brothers, the Paladins of Thunder choose a Champion of the Emperor from their ranks during the Weeping Vigil. If a Space Marine cries a single blood tear it is considered as a chosen by Dorn himself and it's given a dual handed chainsword; similar in fashion to their primarch. During the next Feast of Blades, the hopes of the chapter rest upon this chosen warrior.
 * The Oath of Fidelity: Once every 20 years, the chapter celebrates the day their first Magister Medicae fell in combat and both them and the Crimson Fists made a promise of blood and fidelity to eachother. Both 1st Captains gather onboard the battle barge Rynn's Resilience and cut eachothers hands and recite the words that Pedro Kantor said to Aemilius Castor.
 * The Pilgrimage: Following the example of Robute Guilliman once he awakened, the Magister Medicae must go in a pilgrimage to Inwit, the place where Rogal Dorn was raised and bring with him the fur of the biggest white bear he can find and wear it until death, were the cape will go into the Inner Sanctum of the Fortress-Monastery.