Bernadottic Wars
The Bernadottic Wars were a series of wars fought between the Beriquois Empire, ruled by Longin Bernadotte, and other nations on the continent of Teudallum, including each of its neighbours, Khyragus, Nikolia and Slovertia, as well as the fledgling Federation of Kobolis, which formed as a result of a Beriquois invasion, and the Cadenzan Empire.
The wars were precipitated by some conflict or other which led to the overthrow of the Beriquois monarchy, and the flight of Charles Philippe of the Beriquois house of Bourbon (different name pls though Hifax) to Cassonne, where he attempted to establish a government-in-exile. In Berique, power was quickly seized by Bernadotte, who embarked on a series of campaigns against his neighbours in his efforts to consolidate his position. This began with the Beriquois-Khyragan War, a stunning victory for Berique which caused alarm across Teudallum and western Astyria at the sudden upset to the regional balance of power.
Other things happened elsewhere, like Something in Nikolia and Kobolis doing things, which helped the wars motor along toward their resolution. This started the whole process of Kobolian unification and sent them off seeking diplomatic support and recognition.
The battles fought on the Mederano Peninsula were among the largest in Astyrian history to that point and saw tens to hundreds of thousands of troops on each side. The involved nations transformed into prototypical war economies, devoted entirely to the defeat of their enemies, and the rest of Astyria looked on with concern as the escalating conflict led trade networks in northern Teudallum to falter and collapse. The Cadenzan Republic intervened in support of Kobolis by placing a blockade on Berique's ports that was the largest naval campaign of the war, involving hundreds of ships. It allowed Kobolis to get its act together but things went awry at some point and Cadenza found itself forced to sue for peace before the end of the war, yielding its territory in Cadenzan Kamalbia.