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To his word the Emperor asked the awakened Angron whether he would wish to be saved. The man, in a fury, declared that he will never sleep lest the chance someone tries to ‘save’ him.
With those words the newly rechristened World Eaters went into the Crusade. Their path quickly became a deliberate wrecking ball of destruction which was equal to an exterminatus. Angron, above all others, did not care how many of his sons died when they were released upon a world.
It was known to TalOS thanks to the Tech Priests of the orders Angron enforced. If a planet was not culled within the time period that the Primarch declared at the moment of their arrival, then all those upon the planet will find themselves killed by the hands of their own Father.
There was no reason for this. Even Perturabo who had indeed declared the deaths of his own sons, had a reasonable sense of mind when doing so. Here Angron was simply doing it because he hated everyone and everything.
A Prisoner of obligation without the power to attack the Emperor. Angron was still a Primarch and knew that if he tried anything then the Wolves of Fenris would be thrown at them. And at that moment they will lose. If there is ever a rebellion though one can guarantee that Angron will be one of its founders.
As for the rest of the Crusade the battles were won handily. Entire swaths of space were now being claimed as the Astartes were unimpeded by a foe as powerful as them. As TalOS understood it the Galactic Core was sieged and gained by Rogal Dorn, with the vassalage of the Squats as his bounty. For that the Mechanicum was flooded with new technologies of what was a previously powerful Empire.
It was at this time that the One Hundred Year anniversary of the Great Crusade was struck. To this event the entirety of the Great Crusade found itself crawling to a halt as the Emperor returned to Terra for the celebration.
In addition to this, all of his sons were called upon to attend the event. Only Angron and Jaghatai Khan were missing from the event, one either too angry or the other too aloof within the Galaxy to care what was happening within the core of the Empire.