The Iron Warriors warband known as the Siege Breakers are a faction of the 8th Grand Company. When the Iron Warriors legion laid waste to Terra the Siege Breakers had held a bastion on a planet near the Badab system. When Horus lost his war the Iron Warriors like all the other legions fell back to the Eye of Terror, the Siege Breakers managed to hold onto their bastion for many years as it was a secluded planet often affected by warpstorms. About five hundred years after the Horus Heresy the Blood Angels learnt of the Iron Warriors fortress and despatched a company to rid of the cancer. The Iron Warriors held out against the Angels for almost a year despite various drop pod assaults, with assistance from the Imperial Fists and Rogal Dorn himself the Siege Breakers fled their former bastion but not before unleashing virus torpendos from the bastion, parts of the planet are now unhabitable as permanent reminder of the Iron Warriors thousands of years later.
Over the years the Siege Breakers became like any other warband of the former legions and raided the Imperium whenever they could taking resources, weapons, slaves and more importantly the dead bodies of enemy Space Marines. The geneseed from the fallen enemies was extracted and implanted into slaves which rebuilds the Iron Warriors ranks. All the actions of the Siege Breakers were lead by Warsmith Koro Bandhu who followed the path of the Blood God. With many razed planets behind Bandhu and geneseed stolen from loyalist Space Marines which was corrupted in the name of the Dark Gods saws Bandhu elevated to Daemon Prince, his olympian artificer armour becoming tatters and part of his body while his skin changed colour to match that of a Bloodletter, Bandhu was renamed the Blood Prince.
It is unclear when and exactly how, a company of Blood Angels come seeking the Siege Breakers looking for revenge from the event just after the Horus Heresy. A powerful Blood Angel Librarian managed to defeat the Blood Prince and cast his form into the warp. The Siege Breakers became inactive for a time and became misdirected until a Champion of the Chosen among the warband known as the Ironsmiths come forward and took leadership of the Siege Breakers. The Champion known as Gerrox entered many pacts with Daemons to locate the entity of the Siege Breakers daemon lord in the warp, after many thousands of years searching Ferrox finally located the Blood Prince.
During a Blood Angel defense against Orks on a planet of the Imperium the Iron Warriors struck. The Iron Warriors seized ground from the Orks as a forward operations base and then laid siege to the city from one side while the Orks struck the other. The Blood Angels were hard pressed with two attacks coming from different fronts against enemies which wasn't even working together. During the battle Captain Haftrion famous for his Wing Striker attack formation was captured by the Iron Warriors and sacrificed among with several other Blood Angels to the Daemons Ferrox had made pacts with, with the Daemons satisfied the Blood Prince was released from the clutches of the warp back into reality.
Gerrox for his reward for destruction and revenge on a enemy and also releasing the Blood Prince was also risen to Daemon Prince courtesy of the Blood Prince forming Gerrox into his own image. Gerrox appeared like the Blood Prince but due to his pacts been made with Nurgle Daemons more than any other his form took on a deathly corpse appearance, he was renamed the Corpse Prince.
Unfortunately for the Siege Breakers the leadership of two Daemon Princes attracted too much attention from the Imperium. While the Princes razed a world and created the Greater Daemon known as Firemane, a Daemon created from the Iron Warriors themselves a company of Blood Angels struck with the Wing Striker attack formation, the former company of Captain Haftrion had come to avenge him. The Iron Warriors were cut down and destroyed with Firemane cast back into the warp along side both Princes and many Chaos Space Marines destroyed. Only a few Obliterators remained which deserted battle. With that the remaining Siege Breakers warband dissolved and a threat to the Imperium has been vanquished; until the Princes escape the warp at least.
The Siege Breakers was made up of approximately five hundred Chaos Space Marines which had access to numerous Chaos Rhinos, Drop Pods and limited Land Raiders. Most used wargear amongt the Chaos Space Marines were meltaguns and plasma guns which fitted in with the Iron Warriors operation for busting bunkers and forming a beachhead or controlling strategic areas.
Of the number of Chaos Space Marines in the warband approximately a additional fifty were ranked as Chosen. These Marines were more favoured in the eyes of the Chaos Gods and more battle experieced, majority of them present during the Siege of Terra.
The Siege Breakers has a large Obliterator Cult made up of approximately forty Obliterators. Unlike others of their kind these Obliterators are loyal only to the Iron Warriors as a good portion are either Techmarines of the former legion or traitor Tech Priests which have been swayed by power or joined the Iron Warriors from the Horus Hersey. Many Tech Priests sided with the Iron Warriors along side Titan Legions, it's believed that the Obliterators are created by dark technology and combination of warp corruption.
* If you're wondering why the Iron Warriors were destroyed it's because I've recently sold them on Ebay. Maybe some day I'll return to
CSM, but for the moment it's time the Iron Warriors went to a new home.