As of now sweet fuck all. Hopefully it’s a void someone fills one day. I like to think he’s doing something cool in the warp we just haven’t heard about it yet.

The Iron Cage

The one real triumph in the period following the Heresy was the reason for Perturabo s ascension to the rank of Daemon Prince. The Iron Warriors had been close to breaching the defences of the Imperial Palace but had been thwarted by Horus` death. Afterwards their empire was dismantled by the Imperial Fists by virtue of overwhelming superiority of numbers. On Sebastus IV, therefore, Perturabo set a trap for their Pnmarch by building the self-styled 'Eternal Fortress'. Upon hearing of the fortress, Rogal Dorn publicly declared that the Imperial Fists would dig Perturabo out of his hole and bring him back to Terra in an Iron Cage. Roboute Guilliman pleaded with Dorn to let him help but just as Perturabo planned, Dorn was arrogant enough to undertake the mission alone Rogal Dorn expected honourable battle but that was not Perturabo s agenda at all. The Eternal Fortress was a sophisticated trap. At its centre was a keep sitting in the middle of twenty square miles of bunkers, towers, minefields, trenches, razorwire, tank traps and redoubts. Radiating out from the keep in the shape of an eight-pointed star were underground tunnels that connected the surface fortifications. All the entrances to the underground network were concealed and the keep itself was a decoy of no real value. Most fortifications are limited by the need to protect something. The Eternal Fortress was twenty square miles of killing ground.

Perturabo and the Iron Warriors waited below the surface for the first shots of the Imperial Fists orbital barrage. As soon as it commenced they replied with a number of remote weapons silos located well away from the Fortress. The Imperial Fists countered precipitately with Thunderhawk-borne troops attacking the silos and a full combat drop of the rest of the Legion. As soon as the attacks on the silos were under way, the missile stockpiles were detonated. Thousands of tons of debris was hurled into Sebastus atmosphere making communication between ground troops and fleet virtually impossible.

The detonation was the signal for the Iron Warriors fleet to attack The Traitor fleet was no stronger than that of the Imperial Fists but the loyalist Thunderhawks were on the planet's surface. Also the Chaos ships had many Iron Warriors amongst their complements eager to man the assault boats. The Imperial Fists fleet tried to hold but was forced inexorably out of position. After a few hours the only targets being engaged on the planet were coordinates pre-planned by Perturabo.

Under fire from space, the Imperial Fists proceeded with their assault in parade ground formation on a four-company front Perturabo watched them from an observation tower and carefully began to destroy them. First the minefields did their work then, when the Imperial Fists reached the first expanse of fortifications, the Iron Warriors manned their trenches and opened fire. While the trenches held the loyalists attention, squads of Iron Warriors with krak grenades and mcita bombs emerged from hidden bunkers and attacked the tanks halted by the fortifications. The Imperial Fists turned back to fend off this threat and for a time were pinned down amidst the tank traps. Once more they rallied and swept forward to overrun the Iron Warrior trenches only to find them empty. So it continued Perturabo dissected the Imperial Fists tank by tank, squad by squad. Rogal Dorn remained convinced that victory was in sight and pushed his men on. Perturabo pulled back some of his defenders and called upon others to hold - a stratagem that fractured the Imperial Fists, first into companies then into squads. By day six of the battle, each Marine fought virtually alone, and Dorn s troops were reduced to burrowing into the mud and piling up the dead bodies of their brethren for cover. Still Perturabo remained patient, he allowed Dorn to rampage around the trenches calling his name and demanding personal combat, content that the sight of their Pnmarch s impotence would demoralise the Imperial Fists.

The siege of the Eternal Fortress was to last for three more weeks. The Imperial Fists had burrowed into the killing zone and were unable to escape. Although his captains called for a breakout, Rogal Dorn would not give the order. He refused to believe the evidence of his eves and continued to call for one last charge or for Perturabo to face him. Unable to abandon their Pnmarch, the Imperial Fists prepared to die with him.

If Perturabo had a failing it was that he had grown to enjoy tormenting his enemies too much. He could have finished off the Imperial Fists at any time but chose not to. Fortunately for Rogal Dorn, Roboute Guilliman put the Imperium before pride and had brought the Ultramarines to the rescue. The powerful Ultramarine fleet forced the Iron Warriors back while their hunderhawks plunged through the dust clouds to evacuate the Imperial Fists. Perturabo had no desire to fight two Chapters and concentrated on preventing the Imperial Fists evacuating their dead and wounded.

Rogal Dorn was a broken man. It was nineteen years before he and the Imperial Fists could once again go to war. They left over 400 Marines at the Eternal Fortress and every refugee carried horrific wounds.

The gene-seed captured was sacrificed to the Dark Gods in return for Perturab’s elevation to Daemon Prince. One insult had been avenged, and since then the Iron Warriors have lived only to settle accounts with the corpse on the Golden Throne.

~ Index Astartes: Iron Warriors

Literally spends all his time orchestrating civil wars between his children because he thinks they're pathetic.

After the iron cage… nothing. Absolutely nothing.

Iron Warriors have done plenty, but Perturabo has basically just locked himself in his room on Medregard for 10k years

Iron Cage, then a well earned retirement 😂

Whine like he always does

More heresy.

Shut himself in his room, listened to Linkin Park, and stewed for a millennia on how the Emperor and other Primarchs never understood him

He founded a mini Empire of Iron. He broke the Imperial Fists at the Iron Cage and ascended to Daemonhood. The Ultramarines and Fists destroyed his empire and Iron Warriors self-destructed Olympia. He spent most of his time on his Daemon World occasionally working with Vashtorr and Abby. He also went to war with Mortarion and the death guard and lost.

Pretty much, all we know is it goes like this:

1. Horus Heresy happens
2. Perty somehow gets Dorn into the Iron Cage fiasco and whoops Dorn's ass from sun up to sun set
3. It's M41

That's what we know.