Nicomedia under the Great Persecution
Nicomedia held a central place in the persecution under Diocletian because the city served as a chief imperial seat in the eastern provinces, which made the visible suppression of Christianity there a matter of imperial policy. Eusebius records that the opening act of the persecution in 303 was the demolition of the city's principal Christian church and the public burning of the sacred books, followed by edicts compelling sacrifice to the gods of the state.
Nicomedia accordingly figures in the calendar as the place of numerous martyrdoms of this period, including the bishop Anthimus, large numbered companies of the faithful, and, by Byzantine tradition, a great multitude commemorated as the Twenty Thousand Martyrs burned in their church at the Nativity. The Ten Virgin-Martyrs belong to this same body of Nicomedian witnesses, distinguished in the calendar by their consecrated virginity and by their separate commemoration on the last day of the year.