«ANGELUS DOMINI». — This phrase is commonly used to denote the pious devotion by which, at the sound of the morning, midday, and evening bells, the faithful are invited to recite three Hail Marys, interspersed with three Gospel verses commemorating the Incarnation of Jesus and in praise of the Virgin Mother. The devotion took its name from the first of these verses: A. D. etc.
Just as the present form of the Hail Mary was formed and spread throughout the Middle Ages until it reached the form now universal in the Church, so too can this be said of the devotion of the Angelus. Indeed, from the 13th century, it was common to invite prayer with the Our Father and the Hail Mary at the sound of the bell at the hour of compline and curfew. St. Bonaventure exhorted his friars to inculcate this pious practice among the faithful, and John XXII granted a special indulgence for Rome in this regard in 1327. From the beginning of the 14th century, the use of a similar prayer at the sound of the morning bell is attested in many places; this usage became customary in that century and the following one. The midday bell for prayer was limited in some dioceses to Fridays only; it was extended to every day when Callistus III, in 1456, invited prayer for victory against the Turks. From these customs, the practice still in use today was formed from the 16th century onward, and popes Benedict XIV and Leo XIII enriched it with special indulgences.