Gregory Thaumaturgus
When the calendar system of Anno Domini was first introduced by Dionysius Exiguus in AD 525, he assigned the beginning of the new year to March 25 since, according to Catholic theology, the era of grace began with the Incarnation of Christ. The first certain mentions of the feast are in a canon of the 656 Council of Toledo, where it is described as celebrated throughout the church. The 692 Council of Constantinople "in Trullo" forbade observance of any festivals during Lent, excepting Sunday and the Feast of the Annunciation. An earlier origin had been claimed for it on the grounds that it appeared in manuscripts of the sermons of Athanasius and Gregory Thaumaturgus but they were subsequently discovered to be spurious.