At this time the immense Roman Empire was divided into Western and Eastern halves, governed by two independent emperors and their corulers called "Caesars." Constantius Chlorus was Caesar in the Western Roman Empire. St Constantine was born in 274, possibly at Nish in Serbia. In 294, Constantius divorced Helen in order to further his political ambition by marrying a woman of noble rank. After he became emperor, Constantine showed his mother great honor and respect, granting her the imperial title "Augusta."
After the death of Constantius Chlorus in 306, Constantine was acclaimed by the army at York as emperor of Gaul and Britain. The first act of the new emperor was to grant the freedom to practice Christianity in the lands subject to him. The pagan Maximian Galerius in the East and the fierce tyrant Maxentius in the West hated Constantine and they plotted to overthrow and kill him, but Constantine bested them in a series of battles, defeating his opponents with the help of God. He prayed to God to give him a sign which would inspire his army to fight valiantly, and the Lord showed him a radiant Sign of the Cross in the heavens with the inscription "In this Sign, conquer."
[The following night, our Lord Jesus Christ appeared to him in a dream and declared to him the power of the Cross and its significance. When he arose in the morning, he immediately ordered that a labarum be made (which is a banner or standard of victory over the enemy) in the form of a cross, and he inscribed on it the Name of Jesus Christ. On the 28th Of October, he attacked and mightily conquered Maxentius, who drowned in the Tiber River while fleeing. The following day, Constantine entered Rome in triumph and was proclaimed Emperor of the West by the Senate, while Licinius, his brother-in-law, ruled in the East. But out of malice, Licinius later persecuted the Christians. Constantine fought him once and again, and utterly destroyed him in 324, and in this manner he became monarch over the West and the East.]
After Constantine became the sole ruler of the Western Roman Empire, he issued the Edict of Milan in 313 which guaranteed religious tolerance for Christians. St Helen, who was a Christian, may have influenced him in this decision. In 323, when he became the sole ruler of the entire Roman Empire, he extended the provisions of the Edict of Milan to the Eastern half of the Empire. After three hundred years of persecution, Christians could finally practice their faith without fear.
Renouncing paganism, the Emperor did not let his capital remain in ancient Rome, the former center of the pagan realm. He transferred his capital to the East, to the city of Byzantium, which was renamed Constantinople, the city of Constantine (May 11). Constantine was deeply convinced that only Christianity could unify the immense Roman Empire with its diverse peoples. He supported the Church in every way. He recalled Christian confessors from banishment, he built churches, and he showed concern for the clergy.
The emperor deeply revered the victory-bearing Sign of the Cross of the Lord, and also wanted to find the actual Cross upon which our Lord Jesus Christ was crucified. For this purpose he sent his own mother, the holy Empress Helen, to Jerusalem, granting her both power and money. Patriarch Macarius of Jerusalem and St Helen began the search, and through the will of God, the Life-Creating Cross was miraculously discovered in 326. (The account of the finding of the Cross of the Lord is found under the Feast of the Exaltation of the Cross, September 14). The Orthodox Church commemorates the Uncovering of the Precious Cross and the Precious Nails by the Holy Empress Helen on March 6.
While in Palestine, the holy empress did much of benefit for the Church. She ordered that all places connected with the earthly life of the Lord and His All-Pure Mother, should be freed of all traces of paganism, and she commanded that churches should be built at these places [at the sites of the Crucifixion and Resurrection, in Bethlehem at the cave where our Saviour was born, another on the Mount of Olives whence He ascended into Heaven, and many others throughout the Holy Land, Cyprus, and elsewhere.]
The emperor Constantine ordered a magnificent church in honor of Christ's Resurrection to be built over His tomb. St Helen gave the Life-Creating Cross to the Patriarch for safe-keeping, and took part of the Cross with her for the emperor. After distributing generous alms at Jerusalem and feeding the needy (at times she even served them herself), the holy Empress Helen returned to Constantinople, where she died in the year 327.
Because of her great services to the Church and her efforts in finding the Life-Creating Cross, the empress Helen is called "the Equal of the Apostles." The peaceful state of the Christian Church was disturbed by quarrels, dissensions and heresies which had appeared within the Church. Already at the beginning of St Constantine's reign the heresies of the Donatists and the Novatians had arisen in the West. They demanded a second baptism for those who lapsed during the persecutions against Christians. These heresies, repudiated by two local Church councils, were finally condemned at the Council of Milan in 316.
Particularly ruinous for the Church was the rise of the Arian heresy in the East, which denied the Divine Nature of the Son of God, and taught that Jesus Christ was a mere creature. By order of the emperor, the First Ecumenical Council was convened in the city of Nicea in 325.
318 bishops attended this Council. Among its participants were confessor-bishops from the period of the persecutions and many other luminaries of the Church, among whom was St Nicholas of Myra in Lycia. (The account about the Council is found under May 29). The emperor was present at the sessions of the Council. The heresy of Arius was condemned and a Symbol of Faith (Creed) composed, in which was included the term "consubstantial with the Father," confirming the truth of the divinity of Jesus Christ, Who assumed human nature for the redemption of all the human race.
One might possibly be surprised by St Constantine's grasp of theological issues during the discussions at the Council. The term "consubstantial" was included in the Symbol of Faith at his insistence.
[Falling ill near Nicomedia, he requested to receive divine Baptism, according to Eusebius (The Life of Constantine. Book IV, 61-62), and also according to Socrates and Sozomen; and when he had been deemed worthy of the Holy Mysteries, he reposed in 337, on May 21 or 22, the day of Pentecost, having lived sixty-five years, of which he ruled for thirty-one years. His remains were transferred to Constantinople and were deposed in the Church of the Holy Apostles, which had been built by him (see Homily XXVI on Second Corinthians by Saint John Chrysostom).]"
(taken from: http://ocafs.oca.org/FeastSaintsViewer.asp?SID=4&ID=1&FSID=101452, and quotes in brackets taken from: http://goarch.org/chapel/saints_view?contentid=62&type=saints&date=5/21/2009&D=TH)
The following quote about St. Constantine at the First Ecumenical Council is taken from: http://www.orthodoxphotos.com/Holy_Relics/St._John_Iacob_the_Hozevite/index.shtml.
"In the History of the Church by the most-wise hierarch Meletius, it says that when the First Ecumenical Council in Nicaea ended, the Emperor St. Constantine the Great rejoiced greatly at the victory of the the Church against the slanderers. The emperor was present at the Council and honored the Holy Fathers with rich gifts, according to their merit, piously kissing the plucked eyes of the devoted Paphnutius with zeal, as well as the hands maimed by the tyrants. He also devoutly kissed all the other confessors, in order to sanctify himself through their wounds, which they suffered in the time of the persecution.
Some of the Council's fathers handed the emperor some complaints against a number of bishops of bad conduct. But the great Emperor Constantine did not even read their papers, nor was he interested in the identity of the accused clerics, but burned the papers in the presence of all, saying: "If with my own eyes I were to see a cleric sin, I would cover him with my mantle, that is with the mantle of the emperor.""
The Life of St. Nicholas mentions how he appeared to St. Constantine in a dream, telling him to free three generals who were wrongly imprisoned. See: http://full-of-grace-and-truth.blogspot.com/2008/12/life-of-st-nicholas-archbishop-of-myra.html, for an account and an icon.
And for one primary source account of the Life of St. Constantine, see that of Eusebius at the following link: http://www.newadvent.org/fathers/2502.htm. This has many details from the life of St. Constantine, many quotes and letters of his. As an example, the following quote is of St. Constantine's request for Baptism, and of the sacrament itself:
"'The time is arrived which I have long hoped for, with an earnest desire and prayer that I might obtain the salvation of God. The hour is come in which I too may have the blessing of that seal which confers immortality; the hour in which I may receive the seal of salvation. I had thought to do this in the waters of the river Jordan, wherein our Saviour, for our example, is recorded to have been baptized: but God, who knows what is expedient for us, is pleased that I should receive this blessing here. Be it so, then, without delay: for should it be his will who is Lord of life and death, that my existence here should be prolonged, and should I be destined henceforth to associate with the people of God, and unite with them in prayer as a member of his Church, I will prescribe to myself from this time such a course of life as befits his service.' After he had thus spoken, the prelates performed the sacred ceremonies in the usual manner, and, having given him the necessary instructions, made him a partaker of the mystic ordinance. Thus was Constantine the first of all sovereigns who was regenerated and perfected in a church dedicated to the martyrs of Christ; thus gifted with the Divine seal of baptism, he rejoiced in spirit, was renewed, and filled with heavenly light: his soul was gladdened by reason of the fervency of his faith, and astonished at the manifestation of the power of God. At the conclusion of the ceremony he arrayed himself in shining imperial vestments, brilliant as the light, and reclined on a couch of the purest white, refusing to clothe himself with the purple any more."
(taken from: http://www.newadvent.org/fathers/25024.htm)
And finally, the life of St. Paisios is recounted a vision he received of St. Constantine the Great, in which he praises the Monastic Life (see the previous post: http://full-of-grace-and-truth.blogspot.com/2008/10/vision-of-st-paisios-of-st-constantine.html)
Many of the churches built by St. Helen still exist to this day. These include (besides those listed above) the Chapel at the Burning Bush on Mount Sinai (http://www.sinaimonastery.com/en/index.php?lid=65), the Church of Ekatontopyliani (Church of One Hundred Doors) on the Greek island of Paros (http://www.ekatontapyliani.org/), the Church of the Holy Cross in Rome (Santa Croce: http://www.sacred-destinations.com/italy/rome-santa-croce-in-gerusalemme.htm), etc. The Church of the Holy Apostles in Constantinople was also built by Sts. Constantine and Helen, however almost nothing remains of it to this day, and a mosque has been built over it (http://www.sacred-destinations.com/turkey/istanbul-church-of-holy-apostles.htm).
May Sts. Constantine and Helen intercede for all of us and help us!
Apolytikion in the Plagal of the Fourth Tone
He beheld the image of Your Cross in the Heavens and, as Paul, he too did not receive the call from men. Your Apostle among Kings placed the care of the Royal City in Your hands. Through the intercessions of the Theotokos, O only Loving Lord, keep it ever in peace.
Today, Constantine with his mother Helen present the Cross, the most precious wood. It shames unbelievers. It is a weapon of faithful kings against their adversaries. A great sign has come forth for us which is awesome in battle.
Christ is risen from the dead, by death, trampling down upon death, and to those in the tombs, bestowing life!