Population: 5.5M
Capital: Orailles
Ruler: King Armaud Martois
Senesia, politically separated from the rest of the continent, was able to forge its own path, that being as a seat of learning and knowledge. Arcane arts flourished as academies sprung up one after another. Because it was never really threatened by conflict, their military is notably lacking. However, they well compensated for that with their expertly trained magicians. Even one Senesian mage is a boon on any battlefield.
This specialization in magic, however, came with drawbacks. Those who cannot cast spells, even though all people are capable to some extent, are seen as lazy and fit only for menial jobs. There is heavy classism between the casters and non-casters, and there is an unfortunately lucrative industrial and cultural complex that profit from this divide. King Armaud, to his credit, has not done anything to further this divide, though he's done little to narrow it. He instead petitioned architects to build an elaborate mansion to house Senesia's highest-ranking nobles, where they indulge in decadent entertainment, distracting them from continuing to torment the lower, magicless classes.
The cultural separation has lead to shaky relations with the other two Kingdoms, in particular their lazy response to the growing Imperial threat. It was only recently that King Armaud accepted the call to arms, but to many it may have unfortunately come too late.
It is unknown what the "final straw" was that prompted King Armaud to declare war on the Empire. The optimists say it was due to the other nations' fall, or perhaps the invasion of the Perisone islands that triggered the change in heart. The more cynical say that it's due to Dion's shipment of wine, condiments, and other luxuries annoyed the upper classes enough to provoke war.