The only information that has been passed down is contained in chap. 16 of Historia Ecclesiastica – the History of the Church - by St. Eusebius (265-340) the learned bishop of Caesarea, who mentions him when telling of the many Christians, imprisoned together with the Montanists (those who embraced the heresy of Montanus, a 2nd century Phrygian priest who preached the end of the world), at Apamea in Phrygia, where he suffered martyrdom. Caius was a native of Eumenia, also in Phrygia, and together with other Christians refused to the end to join the Montanists and their false doctrine. This refusal was considered by ancient writers to be proof of the vigor with which the early Church opposed heresy. There is disagreement regarding the date of martyrdom. Most martyrologies say it occurred under Marcus Aurelius or Commodus. However this appears to be false and that his death can be dated back to the time of the emperor Septimius Severus (193-211), therefore at the beginning of the 3rd century. What type of martyrdom he suffered is mentioned neither in texts nor in the various martyrologies, which refer to him in connection with other groups and places and is therefore commemorated on different days. Unfortunately, this was the situation of the time of the early Christians, which also seemed to affect those who perhaps had recorded the names and manner of death of previous or contemporary martyrs, thus causing any historical information to be lost.