The War Of The Prisms, also known as the Prism's War or the False Prism's War, depending on the views of the person talking about it, was the civil war fought between brothers Dazen and Gavin Guile over who would become Prism. Both brothers were full-spectrum polychromes and eligible to occupy the position, but given that the teachings of the Orholamic Faith decree that only one Prism is born in a generation, this resulted in a crisis of faith in the Satrapies as well as social upheaval.
The war's prelude began when Dazen discovered that he was a full-spectrum polychrome, upsetting Gavin, who had been named Prism, and who saw his brother as a threat. However, the situation might never have developed any further except that Andross Guile, father of Dazen and Gavin, made overtures to Rissum White Oak about marrying one of his sons to Rissum's daughter Karris. Andross, being a clever, conniving, and amoral man, told his sons that his plan was to tell Rissum that he wanted Gavin to marry Karris, meanwhile Dazen would seduce her. Andross would arrange it so that he and Rissum would walk in on them, Andross would pretend to be furious, and to save Karris' dignity (and, more importantly in the eyes of her father, the family's dignity,) Karris would be wed to Dazen, leaving Gavin, Andross' oldest son and greatest bargaining chip, free to marry someone else. The plan went awry when Karris and Dazen fell in love, and planned to meet at the White Oak estate and run away together. Rissum found out somehow, and kidnapped Karris, holding her prisoner in the White Oaks' apartments on Big Jasper. Meanwhile, Dazen arrived at the estate, and was told by a maid that Karris was inside. As soon as he stepped into the house, all seven of Karris' brothers attacked him, claiming that they were going to teach him a lesson for shaming their family by beating him to death. Dazen, who normally would not have been able to draft at night, split light for the first time, using the light from a nearby fire to draft all of the colours, and fought back against the brothers, killing 6 of them, and grievously wounding the seventh, Koios. During the battle, the mansion caught on fire, and Dazen fled. Unbeknownst to anyone until 16 years later, Koios survived his injuries and the burns he suffered in the fire, and went into hiding, only to emerge after 16 years as the Colour Prince, a polychromatic wight leading a insurrection against the Chromeria. As the news spread of the battle in the White Oak mansion and the blaze that engulfed it, the people assumed that Dazen had burned it down intentionally and maliciously.
The intervening events have not been elaborated on, but some series of events escalated the hostilities further after this, leading to all-out war.
The war lasted for only four months, but in that time, 200,000 people died, according to Gavin.
Ultimately, Gavin and Dazen faced off in one-on-one combat in the final battle of the war, at Sundered Rock. There, Dazen defeated his brother, but chose to spare his life and assumed his brother's identity, feeling that those who allied with Gavin were far better prospects to govern the Satrapies than his own allies, who were mostly mercenaries, psychopaths, and disreputable folk of every sort.