A feast that began in tenth century Constantinople, is no longer officially celebrated in the Orthodox Church. It was a feast that celebrated the Union of the Great Church, namely the Church of Constantinople. It was celebrated on the Sunday that fell between July 6th and 12th, when the Tomos of Union was read from the ambon in all the churches of Constantinople. It is not known whether or not this feast was celebrated outside of Constantinople, which may perhaps explain why it did not survive.
Emperor Leo VI caused a major scandal with his numerous marriages which failed to produce a legitimate heir to the throne. His first wife Theophano, whom Basil had forced him to marry on account of her family connections to the Martinakioi, and whom Leo hated, died in 897, and Leo married Zoe Zaoutzaina, the daughter of his adviser Stylianos Zaoutzes, though she died as well in 899. Upon this marriage Leo created the title of basileopatÅr ("father of the emperor") for his father-in-law.
After Zoe's death a third marriage was technically illegal, but he married again, only to have his third wife Eudokia Baiana die in 901. Instead of marrying a fourth time, which would have been an even greater sin than a third marriage (according to Patriarch Nicholas Mystikos) Leo took as mistress Zoe Karbonopsina. He married her only after she had given birth to a son in 905, but incurred the opposition of Patriarch Nicholas. Replacing Nicholas Mystikos with Euthymios in 907, Leo got his marriage recognized by the Church (albeit with a long penance attached, and with an assurance that Leo would outlaw all future fourth marriages).
Patriarch Nicholas was exiled to his own monastery, though he regarded his deposition as unjustified so he involved Pope Sergius III in the dispute. About the time of the accession of Leo VI's brother Alexander to the throne in May 912, Nicholas was restored to the Patriarchate. A protracted struggle and schism with the supporters of Euthymios followed, which did not end until the new Emperor Romanos I Lekapenos promulgated the Tomos of Union on 9 July 920, after a synod of both sides was summoned to make its official decrees on marriage, which caused dynastic issues in the empire. As John Skylitzes writes in his historical synopsis: "In the month of July, the eighth year of the indiction, the Church was united. The metropolitans and clergy who had been at odds and differed from each other in support of the patriarch Nicholas or of Euthymios were reconciled."
From then on, on the Sunday that fell between July 6th and 12th, the Tomos of Union was read from the ambon in all the churches of Constantinople. The Church decreed that third marriages were permissible, though there were limitations: a man over forty, for example, who already had children, was not allowed to marry for a third time. Fourth marriages were absolutely prohibited. Some believe that the famous mosaic of Emperor Leo VI prostrating before Christ in Hagia Sophia (see photo above) dates to this time, and depicts the submission of the emperor and the triumph of the Church.
Hieromonk Matthew Blastares writes more about this in the fourteenth century:
'Basil the Great in his fourth canon states, “We hold the custom of five years’ excommunication for trigamists when the marriage is clearly not dissolved. However, we no longer call such an affair marriage, but polygamy, or rather fornication that has been tempered, i.e., not dissolved, but reduced; limited to one woman. Wherefore, the Lord also said to the Samaritan woman, who had five husbands in turn, “He whom you have now is not your husband,” because they that go beyond the limit of digamy are no longer worthy to be called by the name of husband or wife.” However, he states that “it is not altogether necessary to bar them from the Church, but only for their punishment to be spent in the places of the hearers and of those that stand, not however, in that of the weepers.”
But also, again in canon fifty, he states, “There is clearly no ecclesiastical law of third marriage. Nevertheless, we view such things as defilements of the Church. However, we do not submit them to public condemnations because they are more preferable than unrestrained fornication.” Thus, we do not condemn the practice so as to also dissolve them, but according to the Tomos of Union which will be discussed shortly, by its decisions and command, we accept these marriages.
Gregory the Great, who is surnamed the Theologian, stated, “The first marriage is legal, the second is a concession, the third is a transgression of law, and one beyond this, the life of a swine, which does not have many examples of its evil.” (Homily 37.8)
At this time, three marriages were recognized by ancient laws. Emperor Leo the Wise, who entered into a fourth marriage, was subjected to anathema by Patriarch Nicholas [I Mystikos], who required the emperor to quit himself of this union. Because the patriarch was absolutely inflexible, the emperor expelled Nicholas from the Church, and appointed as patriarch Euthymios Synkellos, a holy man. However, Euthymios, with a majority of hierarchs, contending not only tetragamy, but also trigamy to be illegal, with all zeal hindered the emperor who wished to decree that marriage be extended as far as the fourth for those who so desired. On account of this, a schism arose in the Church, which also sustained the dispute over the throne between Leo VI’s son Constantine Porphryogennetos and the latter’s father-in-law Romanos. At this time, in the year 6428 [920 AD], the so-called Tomos of Union was brought forth, which determined when it is fitting to concede a third marriage for some, excellently places reins on shameless desires of the passions, and it is annually read during July on the ambon. Thus, it states the following toward the end:
“Men who have reached forty years of age, and who cast themselves into a third marriage, inasmuch as they are defilements of the Church, we rule that they are to be excommunicated for five years, and after this expires, they are to approach for Communion once a year, on the venerable day of saving Pascha, after purifying themselves as much as possible by the fast for Pascha. The priest who dares, contrary to the decision, to deem some of these worthy of Holy Communion, will be risking his own rank. We command these things when there are no children from previous marriages. But if in fact there are children, the third marriage will be forbidden. But if a man is thirty and has received a succession of offspring from previous marriages, and nevertheless now joins himself to a third woman on account of the licentiousness of fleshly desire, let him be excommunicated for four years. Afterward, let him partake of Communion three times a year: on the Resurrection Day of Pascha, the Dormition of the undefiled Theotokos, and the feast day of the Lord’s Nativity because the fasts before these days are believed to purify most of the stain absorbed by him. However, if he is childless, this man is worthy of pardon if he chooses a third marriage on account of a desire to procreate children; and, excluded from Communion for three years, he should be treated with customary penalty.”'