Cardinal Bucharis was a member of the Ecclesiarchy during the time of the Age of Apostasy. He was stationed on a planet named Gathalamor, preaching in the name of the Emperor. When warp storms covered a large swathe of the south western region of the galaxy, Bucharis saw it fit to carve himself a vast empire from the Imperium, beginning the Plague of Unbelief. He accomplished this by preaching that Terra had fallen, and that Gathalamor was now the centre of religion. With his two compatriots, Admiral Sehalla and Colonel Gasto, he conquered his empire in a relatively short period.
It was only until he met the Space Wolves did things turn for the worse. He poured millions of men into the conquest of Fenris, the Space Wolves homeworld, but The Fang turned out to be an impossible dream to conquer. He was finally driven back when a Space Wolf fleet arrived in orbit and drove off Bucharis' supporting ships.
The next blow was to come on a planet known as Chiros. It was a rich world covered in forests with a population of only a few million. The forces of Bucharis faced the entire population in arms, snipers placed in hills and ambush teams spread throughout the forests. The entire planet became hostile to Bucharis and his armies and eventually they surrendered to the population of Chiros. Soon, this rebellion spread to other planets that eventually cut a swathe through Bucharis's empire until it reach Gathalamor.
Bucharis soon found out that the rebellions were led by one Confessor Dolan Chirosius. His fury at this was unbound and he ordered the capture of Chirosius. Shortly, Dolan arrived in the Gathalamor system where he was arrested and publicly flogged across the entire planet. He was then put on trial, a mistake to which Bucharis' arrogance blinded him. He let Dolan defend himself, and as such allowed Dolan to preach to every planet in Bucharis's realm. This led to a massed outcry when Dolan's body was flung over the walls of the Cardinal Palace, although it disappeared shortly after this. The populations of all of Bucharis's worlds erupted into rebellion together, as if some driving force commanded them. Bucharis tried to escape on a shuttle, but he was ripped apart by the mob that had raced to the Star Port. Only a pile of ashes marked the spot where Bucharis died.