Initial hostilities were provoked by the evil demigod Iuz, but rapidly expanded to cover most of the Flanaess as opportunistic nations used the conflict to further their own ends. This conflict saw the unification and expansion of the Skullcrush Tribe of the Pomarj as well as a desperate attempt by the Great Kingdom to reclaim its former glories. All of the Flanaess was thrown into turmoil, as every nation of the land waged war against each other. The Pact of Greyhawk eventually ended hostilities, but Iuz's goal was completed: the nations of the Flanaess were irreparably weakened. Now, Iuz simply bides his time, waiting to capitalize on the opening he made for himself.
The wars were ended in 584 when the final truce was brokered in the Free City of Greyhawk, and the wars have come to be named for the city as a result.