Short answers, pulled from the story.
Diocletian assumed power on the 20th of November 284 as a religious conservative faithful to the traditional Roman cult. He preferred older Olympian gods over any new cult of his own.
On the 23rd of February 303 Diocletian ordered that the newly built Christian church at Nicomedia be razed. Its scriptures were burned and its treasures seized while senior clerics lost their ranks and property.
In Constantius's realm covering Britain and Gaul persecution was only lightly enforced or not enforced at all. In Maximian's domain including Italy Spain and Africa persecution was firmly enforced with executions occurring throughout summer 303.
The Edict of Milan posted by Licinius at Nicomedia on the 13th of June 313 became known as universal peace terms for Christians. It commended free unrestricted opportunity of religious worship to Christians after Galerius discontinued persecution in the East on the 30th of April 311.
A man named Eutius was arrested tortured and burned alive becoming the edict's first martyr. African martyrs included Saturninus and the Martyrs of Abitinae executed on the 12th of February 304 in Carthage.