In the year 313 Saint Constantine the Great issued an edict granting Christians religious freedom, and officially recognizing Christianity as equal with paganism under the law. But his co-ruler Licinius was a pagan, and he decided to stamp out Christianity in his part of the Empire. As Licinius prepared his army to fight Constantine, he decided to remove Christians from his army, fearing mutiny. 

The Greek Martyrdom of the Forty Martyrs of Sebaste recounts the martyrdom of forty Christian soldiers in the Legio XII Fulminata (Armed with Lightning) in a lake outside Sebasteia/Sebaste (Lesser Armenia, present-day Sivas in Turkey)), including miracles and visions happening during and after their death.Their martyrdom in 320 for the Christian faith is recounted in traditional martyrologies.

Their feast is celebrated on the 9th of March  in the East and on the 10th in the West. (more in the offices readings)