The Conquest of Falenthiria

Elvish Falenthiria, on the Laibachean Isles has always been a land at war. Considered by many to be a damp, cloudy, and muddy hellhole, ruins of the once mighty Caesennian Empire dot the landscape, and the native Diagan Elves work the lands. It has switched hands time and time again, and faces invasions it has successfully stood against. Now, a new threat faces Falenthiria. Beornraed the Pious is dead at 64, a sickly and most importantly, childless man. The Witan, his council, chose the most prominent of the Falenthirian nobles to succeed him: the ambitious Leofgyd, daughter of Osmund. Across the seas, in the mainland, two hands oppose this. To the south, across the Laibachean Channel lies the Duchy of Aitarn, ruled by the sternly ruthless Osbern "the Clubfooted" of the House of Aitarn. Sworn to the fractured Kingdom of Pourranais and descended from Northern Elvish raiders granted land two centuries past, Osbern's claim to the Falenthirian throne stems from a secret agreement made between himself and Beornraed five years past, as Osbern was a distant cousin. He has denounced Leofgyd acension's and claims she herself acknowledged it years before Beornraed's death. To the north, the King of Geirmundda readies his men. King Hardaknutr "the Noseless," a fearsome warrior, rallies his Northern Elvish subjects, for one last great invasion. His claim to the throne lies in a total rejection of not only Leofgyd's, but Beornraed's rule. He claims his father and Beornraed's predecessor, the similarly childless Godwin, made a pact to succeed the other should one of them die childless. Seeing as how Godwin died childless, Hardknutr argues Falenthiria was his father's, and by birthright, is his in turn. The Invasion of Falenthiria has not yet begun, but the major players are beginning to prepare to attack, or defend... Second scenario, give thoughts, suggestions, and fixes in the comments pls :) Norman conquest but with elves and magic lol