Artei VI, the adopted Star Elf son of Artei V, became Imperial Sovereign in Year 1560. He immediately caused a scandal among Star Elves and Asguardian Dwarfs alike when he stated his belief in Mork and Gork, the twin deities of the race of Orks. Several years later, he professed a belief in Incarnatism as well as the Old Gods of the Star Elves in addition to his worship of the Ork deities.
Many Blue Monarchists and even Moderate Party members in the Imperial Parliament were scandalized by Artei VI's religious beliefs, although Red Monarchists tended to be a bit more forgiving of Artei's eccentric religious beliefs.
However, by Year 1600, armed rebels led by Artei VI's sister (the adopted daughter of Artei V), started a civil war which rocked the Local Group of galaxies and bitterly divided the Star Imperium. Orks tended to be loyal to Artei's government on Alfheim, as did Dark Elves, but interplanetary governments dominated by Sigmarites and Sul-Menites, as did certin races of Aliens took advantage of the chaos of civil war to seize interstellar territory, and the Imperium actually lost much of it's territory by Year 1700.
By the time Artei VI was assassinated in Year 1746 by a religious fanatic and Star Elf who fermented believed in Monotheism, the Star Imperium had lost much of it's territory and was still bitterly divided by civil wars. (See also True Empire.)