The Martyr Eusignius was born at Antioch in the mid-third century. For sixty years he served in the Roman armies of the emperors Diocletian, Maximian Hercules, Constantius Chlorus, Constantine the Great and his sons. Saint Eusignius was a companion of Saint Basiliscus (March 3 and May 22), and he provided an account of his martyrdom. At the beginning of the reign of Saint Constantine the Great, Saint Eusignius was a witness to the appearance of the Cross in the sky, a prediction of victory.
Saint Eusignius retired in his old age from military service and returned to his own country. There he spent his time in prayer, fasting, and attending the church of God. So he lived until the reign of Julian the Apostate (361-363), who yearned for a return to paganism. Through the denunciation of one of the Antiochian citizens, Saint Eusignius stood trial as a Christian before the emperor Julian in the year 362. He fearlessly accused the emperor of apostasy from Christ, and reproached him with the example of his relative, Constantine the Great, and he described in detail how he himself had been an eyewitness to the appearance of the sign of the Cross in the sky. Julian did not spare the aged Saint Eusignius, then 110 years old, but ordered him beheaded.