Klaus I reigned as King of the Holy Kingdom of Faerghus until his death in Imperial Year 861. His three sons, princes with competing claims to the throne, agreed to become archdukes and divide the Holy Kingdom of Faerghus between them into three separate territories. These were the Eastern Kingdom, the Western Kingdom, and Leicester, the last of which had been annexed from the Adrestian Empire by Faerghus after a rebellion in 801. This arrangement precipitated Leicester's secession from Faerghus after the death of its archduke in 881, and the formation of the Leicester Alliance in 901.
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A damaged book in the Shadow Library of Abyss titled "Burnt Remnants of a Report," states that Klaus I was likely assassinated and that his will demanding the Kingdom be divided among his heirs is a forgery.