History of the Jordanis 5th:
Jordanis was originally a forgeworld that produced chimera chassis’ for the imperial guard, because its population was so low, they never required to produce any regiments, the planetary population was just over 1 billion, with nearly half of that being servitors. Located in the eastern sector, Jordanis never had much of a threat from Chaos, and the local Ork population were kept at bay by the local PDF, Eldar were largely uninterested in that planet, the only enemy the local PDF of Jordanis faced was Orks.
Sometime in latter half of M40, the Tau empire started “negotiations” with the planetary governor, Xandron Der Jarveen. After “kindly” telling the tau embassadors to place their truce agreement in where ever their backdoor is, the Tau attacked the planet, due to a solar storm, almost all the defense lasers were out of commission, so the people of Jordanis had no anti-orbit guns functioning.
Within 2 days the Tau had conquered much of the Jarveen continents coastline, and started to press inwards, luckily for the people of Jordanis, the local Ork population controlled much of the forests between the Jarveen coastline and the main industrial hive of Trevonis, the only industrial hive on the planet that produced Leman Russ Tanks, and had access to ancient Plasma STC’s. Xandron was heard commenting that the Tau should have picked somewhere else to attack, and that they should have done their homework first.
The Orks caused the Tau heavy casualties, and bought the PDF forces enough time to build over 200 Leman Russ Main Battle Tanks, as well as muster over 5000 chimera’s, hellhounds, and sentinel walkers, as well as nearly 15000 PDF troops, there was also a single warhound titan named the Imperator vires. Xandron knew this wouldn’t be enough, so he had every planetary telepath send out a call for aid.

The Tau fought fiercely, but wanted to keep the entire planet intact because of their love for technology, and Jordanis was not in short supply. The Orks were even well equipped, most using looted stubbers and bolters, and even had a few looted leman russ tanks. The Tau first tried reasoning with the Orks, which was entirely futile, as the embassadors came back on a pointy stick. The Orks way of fighting was far different from the Tau’s, preferring to be up close with axes and other sharp, pointy objects, where the Tau preferred shooting, the only way to combat the Orks was to use the kroot, as they shared a similar fighting style, but were still no match for the Orks, this process entirely wiped out the strike forces kroot and vespid auxiliaries, all the tau had left by the time they got to Trevonis was their tanks and members of the Fire Caste, not a single kroot survived.
Tau hammerheads were the first to shoot, destroying hundreds of tanks before the first hammerhead fell, with no artillery the imperial forces were doomed, because the Tau had every advantage: speed, firepower, range and (at this point in the battle for Jordanis) numbers. The only advantage was that the forces of Jordanis had about 3 weeks time to entrench in Trevonis, and the fact that there were over 3000 techpriests in Trevonis preparing to collect the planets yearly tithe to the imperium, complete with servitor retinues.
The Imperial forces were able to hold the gates of Trevonis for 3 weeks, until Tau reinforcements arrived to relieve the exhausted strike force, it was about this time that Imperial reinforcements arrived, first to help was the space marines, specifically: the Black Templars Chapter’s 4th company, a 400 strong army, and 50 terminators from the 1st company, these forces were led by Champion Zeus, named after the ancient Terran god because of his bulk and immense strength, his sparking power-armor only reinforced his name.
The Champion and his 450 Space marines were able to drive the Tau back to the beaches of Jarveen, and to this day, many of the Jordanis tanks bear the Cross of the Black Templars Chapter as a reminder of the true hero of their planet. It was only by the Emperors grace that the great titan wasn’t destroyed, it had survived being shot nearly 50 times by hammerhead tanks, after weeks of extensive repairs, the titan was restored to full capacity, and given to the planetary governor as a thank you for losing such vital technology to the enemy, its crew was thoroughly delighted at the news as they had become friends with many of the officers in the Jordanis PDF forces. At the end of the !st war for Jordanis, Xandron enacted reproduction programs to replenish the casualties from the war, and to increase the population to have a larger PDF army.
Due to the loss of many of the construction facilities, Jordanis was forced to form guard regiments from existing PDF forces to compensate the yearly tithe, and the first 5 regiments of Jordanis were created, the first 4 were stationed throughout the sector, the first is stationed on Ultramar and 2nd, 4th, and 5th were sent to Cadia to help a Chaos outbreak, when they returned, they wore Cadian issue armor, and used many Cadian tactics, which was then incorporated into the Jordanis regiments to be produced in the future, during this time, they also fought alongside Ibram Gaunt and his Ghosts and learned many of the secrets of stealth, and also incorporate the Cameoline cloaks into their regiment. Officers in Jordanis regiments also have access to the armor worn by Space Marine neophytes and scouts. The Warhound titan was permanently attached to the Jordanis 5th and was renamed the Jordanis Malleus (Hammer of Jordanis, high gothic).
The Jordanis 5th is recognizable because of its tank paint schemes, as well as its dark, vivid green armor that bears a striking resemblance to the Cadian armor/paint schemes. Jordanis troops are known to use a large amount of plasma weapons, and many of the tanks are equipped with plasma weapons, the usage of plasma weapons comes from that Jordanis is one of the few planets with STC’s to produce plasma weapons. But Jordanis troops also use a variety of special weapons, including shotguns, grenade launchers, meltas and almost every infantry squad in the regiment has a lascannon team, only Sergeant Viktor der Jarveen and his “sneaks” carry an autocannon, and Viktor himself carries a Heavy bolter he “liberated” from a burnt out Leman Russ.
Jordanis, because of its amount of technology, is constantly crawling with mars cultists, and many are attached to the PDF forces as well as the imperial regiments mustered from Jordanis. Techpriests of all walks regularly come to Jordanis to train and become familiar with various machines and vehicles, so seeing a space marine techmarine working alongside other mars cultists in battle isn’t a rare sight, and is actually very common during large campaigns that the Jordanis regiments undergo.