On October 1, the Orthodox Churches celebrate on October 1 (October 28 for the Greek Church) the holy protection of their Queen, the Mother of God and ever Virgin Mary.
This feast, particularly solemnized in the Slavic Churches, was instituted following a vision that St. Andrew, "the Bishop of Christ", had in the 9th century, on a day when a vigil was being celebrated in the Church of the Blacherns in Constantinople (today Istanbul, the largest city in Turkey).
At the fourth hour of the night, while immersed in prayer, the saint raised his eyes to heaven and saw the Holy Mother of God standing above the congregation and covering her devotees with her veil (mamphorion). Andrew verified the reality of his vision with his disciple Epiphanius, who had also witnessed it.
The saint then rushed into the sanctuary, opened the casket containing the relic of the precious veil of the Queen of the world, and, standing before the Holy Doors, spread it over the crowd. The veil was so large that it covered the entire crowd, but it hung in the air, supported by a mysterious force.
The Mother of God then rose towards the heavens, surrounded by a very bright light, and disappeared, leaving the Christian people her holy veil as a guarantee of her kind protection. The Mother of God repeatedly showed this protection to the imperial city and, by extension, to the entire Holy Church.
Adapted and translated from: Library of Marian Writings