The celebration of the Most-holy Theotokos, in honor of her Icon known as the Kazan Icon, was established in thanks for the saving of Moscow and all Russia from the attack of the Poles in 1612. The late 16th and early 17th Centuries are known in Russian history as the Time of Troubles. The nation was attacked by Polish armies, who mocked the Orthodox Faith, and who looted and burned churches, towns and villages. By means of deceit, they succeeded in seizing Moscow. In response to the appeal of His Holiness Patriarch Hermogenes (commemorated on May 12) the Russian people rose up in defense of the homeland. The miraculous Icon of the Most-holy Theotokos was sent from Kazan to join the militia led by Prince Dimitry Mikhailovitch Pozharsky.

In his "Homily on the day of the appearance of the Icon of the Mother of God in Kazan" (celebrated July 8), Holy Hierarch Dimitry of Rostov (commemorated September 21) said: The Mother of God saves from great misfortunes and evils not only the righteous, but also the sinful, but what manner of sinners? Those, who like the prodigal son, return to their Heavenly Father; who lament [over their sins]; who, like the publican, beat their breasts; who are like the sinful woman that wept at the feet of Christ and washed His feet with her tears; those who, like the thief on the cross, confess Him. The Mother of God looks after such sinners and rushes to help them, and saves them from great misfortunes and evils.

Recognizing that the misfortune had been permitted because of their sins, the entire people and militia observed 3-day fast, and turned to the Lord and His most-pure mother for divine help. Their prayers were heeded. Holy Hierarch Arseny (later to become bishop of Suzdal), who was a prisoner of the Poles, sent word that he had had a vision revealing by the intercession of the Most-holy Virgin, God's judgment been had turned to mercy. Inspired by this news, the armies on October 22, 1612 liberated Moscow from the Polish occupiers. The celebration in honor of the Kazan Icon of the Most-holy Theotokos was established in 1649. To this day, that Icon is highly venerated by the Russian Orthodox people.