The Threefold War

The Threefold War is technically three separate wars, but the three wars occurred in close chronological proximity to each other within the same region of the world. Each war was a war of independence, attempting to secede from a larger power.
Originally, the Maritime Principalities controlled over half of the known world, comprising the territories of Tharkenwod, Lagrast, Kaldunsk, and some regions now claimed by the Republic of Humanity. Over time, these regions grew culturally distinct from their sovereigns and fought for independence. The first to secede was Kaldunsk, whose tribes had grown united during the Merchant Princes' reign.
After Kaldunsk's victory over the Principalities, the growing religion around Orasil led many to resent the practices of their country. Uniting as a theocracy, the Lagrasi went to war against the Principalities. The Lagrasi, using dreams to communicate in secret and strategize in special ways, were able to outmaneuver and defeat the mercenary companies hired by the Principalities.
As they began to lose their grasp on their territory and fearing the worst for their remaining lands, the Maritime Princes took extra precautions to ensure neither of the fledgling nations would try to annex this territory. They placed embargoes between the cities they still controlled and the neighboring countries that were formerly theirs, quelled any talk of rebellion, and turned the cities into a near police state. Unbeknownst to them, though, there were underground meetings happening and rebel groups preparing to fight back. This organization grew to span the many cities dotting the region, and all at once the citizenry rose up and fought against the Principalities with the aid of the other two nations. This group then formed the nation of Tharkenwood, also taking possession of the nearby forests and all of the territory between Kaldunsk and Lagrast. 
Though policies and relations have changed between the different nations, the three nations have remained sovereign since this war's end and have become quite powerful and capable of defending themselves from outside threats.