Anglo-Saxon missionaries were instrumental in the spread of Christianity in the Frankish Empire during the 8th century, continuing the work of Hiberno-Scottish missionaries which had been spreading Celtic Christianity across the Frankish Empire as well as in Scotland and Anglo-Saxon England itself during the 6th century (see Anglo-Saxon Christianity).
The Anglo-Saxon mission began in the last decade of the 7th century in Old Saxony, when Saint Boniface urged monks to come to the continental missions, from which their forebears had come: "Take pity upon them, for they themselves are saying, 'We are of one blood and one bone with you.'" The missions, which drew down the energy and initiative of the English church, spread south and east from there. Almost immediately the Anglo-Saxon missionaries came in contact with the Pippinids, the new dominant family in Frankish territories.
Ecgberht of Ripon, who had studied in Ireland, began to organize Irish monks to proselytize in Frisia; many other high-born notables were associated with his work: Saint Adalbert, Saint Swithbert, and Saint Chad. He, however, was dissuaded from accompanying them himself by a vision related to him by a monk who had been a disciple of Saint Boisil (the Prior of Melrose under Abbot Eata). Ecgberht instead dispatched Wihtberht, another Englishman living at Rath Melsigi, to Frisia. Ecgberht then arranged the mission of Saint Wigbert, Willibrord, and others to the heathens.
The earliest monastery founded by Anglo-Saxons on the continent is Willibrord's Abbey of Echternach (698), founded at a villa granted him by a daughter of Dagobert II. Pepin II, who wished to extend his influence in the Low Countries, granted free passage to Rome to Willibrord, to be consecrated Bishop of Frisia; Norman F. Cantor singles this out as the first joint project between Carolingians and the Papacy: "It set the pattern for their increasing association in the first half of the 8th century as a result of their joint support of the efforts of the Anglo-Saxon missionaries."
Notable among these missionaries is Saint Boniface who was active in the area of Fulda (modern Hesse), establishing or re-establishing the bishoprics of Erfurt, Würzburg, Büraburg, as well as Eichstätt, Regensburg, Augsburg, Freising, Passau and Salzburg (739) further to the south-east.
Anglo-Saxon missionary activities continued into the 770s and the reign of Charlemagne, the Anglo-Saxon Alcuin playing a major part in the Carolingian Renaissance. By 800, the Carolingian Empire was essentially Christianized, and further missionary activity, such as the Christianization of Scandinavia and the Baltic was coordinated directly from the Holy Roman Empire rather than from England.
- Thurston, Herbert (1913). "Anglo-Saxon Church". In Herbermann, Charles. Catholic Encyclopedia. New York: Robert Appleton Company.
- North, Richard (1997). Heathen Gods in Old English Literature. Cambridge: Cambridge University Press. p. 59. ISBN 0521551838. Retrieved 15 September 2017.
- Bede, Historia ecclesiastica gentis Anglorum 3.4
- Bede Historia ecclesiastica gentis Anglorum 5.9
- Bede, Historia ecclesiastica gentis Anglorum 5.9, 5.10
- Cantor, Norman F. (1993). The Civilization of the Middle Ages: A completely revised and expanded edition of Medieval history, the life and death of a civilization. New York: HarperCollins. p. 167. ISBN 0-06-017033-6. OCLC 27431806.
- Mershman, Francis (1913). "St. Boniface". In Herbermann, Charles. Catholic Encyclopedia. New York: Robert Appleton Company.
- Casanova, Gertrude (1913). "St. Walburga". In Herbermann, Charles. Catholic Encyclopedia. New York: Robert Appleton Company.
- Mershman, Francis (1913). "Sts. Willibald and Winnebald". In Herbermann, Charles. Catholic Encyclopedia. New York: Robert Appleton Company.
- Tolkien, J.R.R. (1982). Bliss, Alan J., ed. Finn and Hengest: The fragment and the episode. London: George Allen & Unwin. p. 14. ISBN 0-0482-9003-3. OCLC 461852232.