20,000 Christians martyred by order of Diocletian. They were reported to have all been in the single basilica to celebrate Christmas. While there unquestionably was an endless series of martyrs under Diocletian, it’s likely the ancient sources exaggerated the numbers of this incident. And as the Christmas holy day was not celebrated in the East in 303, they were probably gathered for another feast.
- Book of Saints, by the Monks of Ramsgate
- Our Sunday Visitor’s Encyclopedia of Saints
- Roman Martyrology, 1914 edition
- “Martyrs of Nicomedia“. CatholicSaints.Info. 18 October 2013. Web. 2 July 2015. <>