Leygance is a former high ranking member of the Ostian army. After the Bern invasion of Lycia and death of Marquess Hector of Ostia, Leygance formed a rebellion in Ostia with the help of former Lieutenant Devias. The rebel group aimed to take over Ostia then surrender it to Bern to avoid an all out war.
The rebellion lead by Leygance began just as Roy and his company were reaching Ostia. After reaching the capital of Ostia, the city of Ostia, Roy launched an attack to reclaim Castle Ostia.
Devias lead the defensive attack on the outside of the Castle, where he was slain guarding the Castle. The group then entered the Castle to continue the siege, inside the Castle General Leygance lead the last of his forces in a last ditch attempt to defeat Roy's forces. Leygance was killed in the Throne room of Castle Ostia.