The Roman persecution of Christians began in earnest on this date in a.d. 303, as the Roman Emperor Diocletian issued an edict that commanded the demolition of Christian churches throughout the empire; confiscated church property for auction; and exiled Christians from the protections of the law.
The edict is widely credited to Galerius, who served in the office of Caesar (junior emperor) under Diocletian until 305, when he ascended to the office of Augustus (senior emperor).
As Edward Gibbon wrote in The Decline and Fall of the Roman Empire,
This edict was scarcely exhibited to the public view, in the most conspicuous place of Nicomedia, before it was torn down by the hands of a Christian, who expressed at the same time, by the bitterest invectives, his contempt as well as abhorrence for such impious and tyrannical governors. His offence, according to the mildest laws, amounted to treason, and deserved death. And if it be true that he was a person of rank and education, those circumstances could serve only to aggravate his guilt. He was burnt, or rather roasted, by a slow fire; and his executioners, zealous to revenge the personal insult which had been offered to the emperors, exhausted every refinement of cruelty, without being able to subdue his patience, or to alter the steady and insulting smile which, in his dying agonies, he still preserved in his countenance.
The persecutions continued for another eight years. In 311, Galerius issued an edict of religious toleration a few weeks before he endured an excruciating death. Lactantius, a North African Christian who lived at the time of Galerius, described with delight the emperor’s passing in his study De Mortibus Persecutorum (“On the Deaths of the Persecutors”):
He grew emaciated, pallid, and feeble, and the bleeding then stanched. The ulcer began to be insensible to the remedies applied, and a gangrene seized all the neighbouring parts. It diffused itself the wider the more the corrupted flesh was cut away, and everything employed as the means of cure served but to aggravate the disease.
. . . Already approaching to its deadly crisis, it had occupied the lower regions of his body: his bowels came out, and his whole seat putrefied. The luckless physicians, although without hope of overcoming the malady, ceased not to apply fomentations and administer medicines. The humours having been repelled, the distemper attacked his intestines, anti worms were generated in his body. The stench was so foul as to pervade not only the palace, but even the whole city; and no wonder, for by that time the passages from his bladder and bowels, having been devoured by the worms, became indiscriminate, and his body, with intolerable anguish, was dissolved into one mass of corruption.