Fire Emblem: Genealogy of the Holy War
Fire Emblem: Seisen no Keifu
Several hundred years ago, the continent of Jugdral suffered under the strict rule of the Loptyr Empire, whose emperors acted as vessels for their dark god, the Earth Dragon
Loptyr. This changed in the year 643, when twelve dragons under the Divine Dragon
Naga descended upon the city of Darna. The twelve dragons forged a blood bond that bestowed their own power upon twelve warriors that would become the Twelve Crusaders.
After a great holy war spanning across several decades, the Loptyr Empire eventually fell. The Crusaders then parted ways, with seven of them forming the Kingdom of Grannvale, while the remaining five founded their own kingdoms: Isaach, Agustria, Silesse and Thracia, which itself later partially divided into the Manster District.
In the Grann year 757, war was beginning, with the bulk of Grannvale's army deployed to Isaach in retaliation for what they perceived to be an unprovoked strike against Darna. Without the threat of any major opposition, King Bator of neighbouring Kingdom of Verdane took this chance to launch an invasion on Grannvale. His son, Prince Gandolf conquers Jungby Castle and abducts its own Lady Adean. In response to these attacks, Lord Sigurd of Chalphy rallies what forces he can in the defense of Grannvale and pursuit of Adean; he is joined shortly after by his brother-in-law, Quan of Leonster and his sister, Ethlyn.
King Bator's motives remain a mystery, but clues of a dark purpose linger as Sigurd must fight onward in Grannvale's honor.