The Derlavaian War was fought for six years by the main powers in the on the continent of Derlavai.
The war began with the death of the Duke of Bari. With the kingdom without an heir, the kingdom of Algarve moved in to annex it, violating the Treaty of Tortush established at the end of the Six Years' War. The kingdoms of Valmiera, Jelgava, Forthweg, and Sibiu declared war in response to Algarve's actions.
Forthweg drove into northwestern Algarve toward the city of Gozzo, but was quickly driven back by large concentrations of behemoths. Then Unkerlant, seeing an opportunity to regain land it had lost in the previous war, invaded Forthweg from the west. Between the two larger armies, Forthweg fell.
After the defeat of Forthweg a short period of inactivity took place between the warring nations, with Jelgava holding its gains in the Bratanu Mountains in eastern Algarve and Valmiera making only slow advances in the south. Finally Algarve broke the stalemate by driving into northern Valmiera, an area that had been considered too rugged for large operations and therefore weakly defended. Valmiera was conquered in only a month.
Fearing Algarve would pull a similar strategy against them, Jelgavan forces began constructing a series of fortifications along the mountain passes leading into their country. Instead Algarve utilized their air forces by airlifting their troops behind the enemy lines, effectively cutting off the Jelgavan army from its supply lines.
After the defeat of Jelgava, the kingdom of Yanina allied with Algarve, and drove the Lagoans from the Land of the Ice People, while Unkerlant fought a harsh war against Zuwayza in order to regain the lands it lost after the Six Years' War. Algarve did not attempt an invasion of Lagoas, instead invading Unkerlant.