St. Euphemia is commemorated on September 16, the day on which she suffered. On this day is commemorated the miracle-working power of her honorable relics, which was manifested at the time of the Fourth Ecumenical Council in Chalcedon. This Council was convened during the reign of Emperor Marcian and Empress Pulcheria in the year 451, after the death of Emperor Theodosius the Younger. The reason for summoning this Council was the heresy of Dioscorus, Patriarch of Alexandria, and Eutyches, and archimandrite from Constantinople who had spread the false teaching that in Christ the Lord there are not two natures, divine and human, but only a Divine Nature. At this Council, the most prominent roles were played by Anatolius, Patriarch of Constantinople, and Juvenal, Patriarch of Jerusalem. Because a decision could not be reached through debates and testimonies from both sides, Patriarch Anatolius proposed that the Orthodox and the heretics each write down their confession of faith, and that they then be placed into the coffin where the relics of St. Euphemia lay. They all agreed to this. Therefore, the two confessions of faith were written and placed on the bosom of the great-martyr. The coffin was closed and sealed with the emperor’s seal, and soldiers were commanded to watch over it. All the members of the Council then spent three days in prayer and fasting. When they opened the coffin on the fourth day, they found the Orthodox Confession of Faith in the right hand of the saint and the heretical one under her feet. Thus, by the power of God, the dispute was decided in the favor of Orthodoxy. During the reign of Emperor Heraclius, the relics of St. Euphemia were translated from Chalcedon to Constantinople, to the church dedicated to her near the Hippodrome. The iconoclastic Emperor Leo the Isaurian ordered that these relics be thrown into the sea, but the coffin was miraculously transported to the island of Lemnos and was placed in the Church of the Holy Martyr Glyceria. Then, during the reign of the Empress Irene, the coffin with the relics of St. Euphemia was returned to Constantinople, to its former place. From time to time, blood has flowed from St. Euphemia’s relics, to help those who are ill or in misery.
Source: St. Nikolai Velimirovic, The Prologue of Ohrid – Volume Two.
O Euphemia, Christ’s comely virgin, thou didst fill the Orthodox with gladness and didst cover with shame all the heretics; for at the holy Fourth Council in Chalcedon, thou didst confirm what the Fathers decreed aright. O all-glorious Great Martyr, do thou entreat Christ God that His great mercy may be granted unto us.