A union of several tribes, led to the beginnings of this war. The Frenks attacked viciously across the river, and left no survivors as they carved a path through Osismied starting at Orleans. The army of Osismied quickly pushed them back, and shattered their forces. But the Frenks were not finished yet. In recently acquired Parisii, an old Ostavan city, The Frenks waited in ambush and killed the king of Osismied in cold blood. Most of the murderers got away and renewed attacks began upon the nation of Osismied which had now lost all stability. The adopted son assumed the throne, and forced the nation back under his control. The Wesfrenk and Sufrenk armies continued to fight deeper into Osismied. This was considered as the end of the reign of the Derfels.
Then, a deal was struck with the Ostavii city states. Osismied paid for Ostavii Mercenaries and sent them to keep the Suffrenks occupied in the East. They quickly took 3 Frenkish towns, and then with the spoils from war, found it far more likeable to turn around and force the city states into their control.
The Osismii though, began a long march of revenge against the tribes which had attacked their lands and killed many innocents. Heavily outnumbered, the army of Osismied set out on the long march. The Frenks inside Osismied were pushed out or completely crushed, and the Unsullied led a night attack on Orleans. With the Osismii fleet controlling the waters, they quickly gained control of the city. Then, during the march to Tours, the two most powerful Wesfrenk chiefs in the North, only united due to Osismied's counter-invasion, placed their armies side by side in the path of the army of Osismied. King Cernyd knew he could not possibly win a battle against the two tribes. Then one day, his Unsullied scouts had returned telling him of the battle between the two tribes. The Osismii army moved in and attacked from the forest on the other side of the armies, directly into the fray. They found out later it was over a woman. One chief escaped, the one who had caused the battle.
Regardless, it continued on to Tours.
The army, now completely exausted, reached Tours. They marched past it and met with reinforcements to the West of Tours. Tours was taken when the army attacked the walls of Tours and the reinforcements landed inside, the Frenks had mostly surrendered.
Then, another Frenkish threat began to grow to the south, one that called for a kingdom of the Frenks, one that would destroy Osismied and take their land once and for all, killing the current inhabitants. Davinsa, with the remainder of his army of the North, quickly forced the tribes under his control.
The army of Osismied, fully replenished and rested, began another march, this time South. They encountered many Frenkish tribes on the way and it seemed the closer they got to the Frenkstrum, the Frenks were fewer and further between. Sensing something was wrong, Cernyd forced the supply carts up a hill, and set his soldiers to chopping the trees on the hill to make barricades. They flipped some carts over to improve the barricade, and that was when word of the frenks moving in was sent by the scouts. The barricade was finished and an epic multiple day battle ensued where the Frenks first tested the Osismii, and then attacked full force. The Osismii won, and the Frenks scattered into the woods. Severely hurt and cut down to size, Cernyd broguht the army home, and only kept Tours and the lands South of the river, as a buffer to any future Frenkish invasions.