20,000 Christians who were murdered during in 303 in Nicomedia, Bithynia (modern Izmit, Turkey) during the persecutions of Diocletian. Many of them were killed en masse when they were ordered, during Christmas Mass, to sacrifice to idols; when they refused, they were locked in the churches and the buildings burned around them. We know some details of a few of them, but most are known only to God.
- 303 in Nicomedia, Bithynia (modern Izmit, Turkey)
- “20,000 Martyrs of Nicomedia“. CatholicSaints.Info. 27 December 2013. Web. 1 July 2015. <>