During the Scattering, Angron was thrown to a civilized human world far from Terra. He plummeted into the icy mountains of that planet, and not long after a slaver found him, and a scene of carnage.
Surrounding the wounded young Primarch were the corpses of numerous Xenos. Imperial scholars would later theorize that they were Eldar who had foreseen the great bloodshed that Angron would cause and had tried unsuccessfully to stop him.
After being enslaved and nursed back to health, Angron was brought to the planet's capital called Desh’ea. There, he was forced into the techno-gladiatorial arenas, where he proved to be undefeatable and a fan-favorite. Several times he tried to lead his fellow gladiators in revolt, and each time failed.
Yet once, he succeeded and after butchering his way through the crowd he led his rag-tag army into the mountains of the planet, where he lived for several years. The civilized cities sent armies to destroy Angron, but they were all obliterated. Nonetheless, the issue was never in doubt. His forces had little to eat in the barren mountains, and were exhausted from the constant battling.
His fate seemed sealed when seven well equipped armies surrounded Angron and his starving forces. Just as the battle was about to begin, the Emperor of Mankind's Fleet arrived in orbit over the planet. The Emperor teleported directly to Angron's point of deployment with a few trusted Adeptus Custodes.
The Emperor promised Angron a legion made in his image, limitless power, and life-times spent perfecting the Art of Conquest. But, to his surprise, Angron refused. He chose instead to die amongst his comrades while fighting his oppressors. Reluctantly, the Emperor returned to his flagship above.
Yet just as the battle was about to begin, the Emperor teleported Angron against his will back up to the fleet. He could only watch in anguish as those he regarded as his brothers and comrades were quickly annihilated. The Emperor betrayed Angron right from the very start.
Angron was eventually taken to the fleet of the XII Legion, the War Hounds. Teleported to the War Hounds flagship, Angron initially refused to have anything to do with his Legion, and when several Captains tried to talk to him, he brutally killed them, as they had been ordered by the Emperor to not raise a hand against Angron. Eventually, Captain Khârn of the 8th Assault Company managed to form a rapport with Angron, talking about the rituals of Angron's gladiators and the traditions of the War Hounds. Now convinced of their worthiness, Angron took full control over his legion, which he renamed the World Eaters, saying they would form new traditions together. During the course of the Great Crusade, he reaped many victories, although some criticized the extreme and bloodthirsty tactics he used to ensure the destruction of his opponents.