The War of Four Crowns was a conflict between the four Isles that ended on 14th Day, Month of Songs, 1625, with Gristol emerging victorious. Shortly afterward on 2nd Day, Month of Nets, 1626, the Empire of the Isles was created and the last king of Gristol, Finlay Morgengaard VI, was crowned as the first Emperor, becoming Finlay Morgengaard I. In the same year, he abandoned his ancestral home, Castle Morgengaard, made Dunwall the new capital and established a parliament there.
Due to the popular legend of Prince Kallisarr, a Tyvia native who believed in the unification of the four Isles, many people in Tyvia, particularly those from Alexin, supported allying with Gristol and joining the Empire. On the Southern front, the Serkonan King was fighting against the forces of Gristol, and Cullero, renown for its military prowess, bore the brunt of the conflict. That was until Mila and Matias, the Duchess and Duke of Aventa, led a group of nobles and merchants, bribed the Grand Guard to join them to prevent further bloodshed. With the Grand Guard behind them, they ousted the king, inspired Bastillian to change side, and the rest of Serkonos soon fell in line. Morley was the last to give in, after fighting fiercely for their independence.
The end of the war saw the Isles unified under the rule of the Imperial Throne in Gristol while other nations were given various degree of autonomy and participation in the Parliament. Tyvia enjoyed more freedom in self-governance than other islands due to their early support for Gristol. Morley, on the other hand, was under strict scrutiny because of their strong resistance during the conflict. This further widened the rift between Dunwall and Wynnedown, which eventually escalated into the Morley Insurrection in 1801. In Serkonos, the line of Serkonan King was ended and the Dukes protected the empty throne of the Kingdom of Karnaca ever since, representing the entire island.
- The War of Four Crowns was first mentioned in the art book Dishonored: The Dunwall Archives.