The sense of joy and thanksgiving, already evident on the Saturday of St. Theodore, is still more apparent on the first Sunday in Lent, when we celebrate the Triumph of Orthodoxy. On this day the Church commemorates the final ending of the Iconoclast controversy and the definitive restoration of the holy icons to the churches by the Empress Theodora, acting as regent for her young son Michael III. This took place on the first Sunday in Lent, 11 March 843. There is, however, not only a historical link between the first Sunday and the restoration of the icons but also, as in the case of St. Theodore, a spiritual affinity. If Orthodoxy triumphed in the epoch of the Iconoclast controversy, this was because so many of the faithful were prepared to undergo exile, torture, and even death, for the sake of the truth. The Feast of Orthodoxy is above all a celebration in honour of the martyrs and confessors who struggled and suffered for the faith: hence its appropriateness for the season of Lent, when we are striving to imitate the martyrs by means of our ascetic self-denial. The fixing of the Triumph of Orthodoxy on the first Sunday is therefore much more than the result of some chance historical conjunction.
The Triodion gives the text of a special ‘Office of Orthodoxy,’ which is held at the end of Matins or, more commonly, at the end of the Divine Liturgy on this Sunday. The Office celebrates not only the restoration of the holy icons but, more generally, the victory of the true faith over all heresies and errors. A procession is made with the holy icons, and after this extracts are read from the synodical decree of the Seventh Ecumenical Council (787). Then sixty anathemas are pronounced against various heretics dating from the third to the fourteenth century; ‘Eternal Memory’ is sung in honour of the emperors, patriarchs and fathers who defended the Orthodox faith; and ‘Many Years’ is proclaimed in honour of our present rulers and bishops. Unfortunately in many parts of the Orthodox Church today this impressive service has fallen into disuse; elsewhere it is performed in a greatly abbreviated form.
Before the Triumph of Orthodoxy came to be celebrated on the first Sunday, there was on this day a commemoration of Moses, Aaron, Samuel and the prophets. Traces of this more ancient observance can still be seen in the choice of Epistle reading at the Liturgy (Hebrews 11:24-6, 32-40), and in the Alleluia verse appointed before the Gospel: ‘Moses and Aaron among His priests, and Samuel among them that call upon His Name.’
Source: The Lenten Triodion. Mother Mary, of the Monastery of the Veil of the Mother of God, Bussy-en-Othe, and Archimandrite Kallistos Timothy Ware: 1977.