Background to the mission
After the withdrawal of the Roman legions from their province of Britannia in 410, the inhabitants were left to defend themselves against the attacks of the Saxons. Before the Roman withdrawal, Britannia had been converted to Christianity and produced the ascetic Pelagius. Britain sent three bishops to the Council of Arles in 314, and a Gaulish bishop went to the island in 396 to help settle disciplinary matters. Material remains testify to a growing presence of Christians, at least until around 360. After the Roman legions departed, pagan tribes settled the southern parts of the island while western Britain, beyond the Anglo-Saxon kingdoms, remained Christian. This native British Church developed in isolation from Rome under the influence of missionaries from Ireland and was centred on monasteries instead of bishoprics. Other distinguishing characteristics were its calculation of the date of Easter and the style of the tonsure haircut that clerics wore. Evidence for the survival of Christianity in the eastern part of Britain during this time includes the survival of the cult of Saint Alban and the occurrence in place names of eccles, derived from the Latin ecclesia, meaning "church". There is no evidence that these native Christians tried to convert the Anglo-Saxons. The invasions destroyed most remnants of Roman civilisation in the areas held by the Saxons and related tribes, including the economic and religious structures.
It was against this background that Pope Gregory I decided to send a mission, often called the Gregorian mission, to convert the Anglo-Saxons to Christianity in 595. The Kingdom of Kent was ruled by Æthelberht, who married a Christian princess named Bertha before 588, and perhaps earlier than 560. Bertha was the daughter of Charibert I, one of the Merovingian kings of the Franks. As one of the conditions of her marriage, she brought a bishop named Liudhard with her to Kent. Together in Canterbury, they restored a church that dated to Roman times—possibly the current St Martin's Church. Æthelberht was a pagan at this point but allowed his wife freedom of worship. One biographer of Bertha states that under his wife's influence, Æthelberht asked Pope Gregory to send missionaries. The historian Ian N. Wood feels that the initiative came from the Kentish court as well as the queen. Other historians, however, believe that Gregory initiated the mission, although the exact reasons remain unclear. Bede, an 8th-century monk who wrote a history of the English church, recorded a famous story in which Gregory saw fair-haired Saxon slaves from Britain in the Roman slave market and was inspired to try to convert their people.[b] More practical matters, such as the acquisition of new provinces acknowledging the primacy of the papacy, and a desire to influence the emerging power of the Kentish kingdom under Æthelberht, were probably involved. The mission may have been an outgrowth of the missionary efforts against the Lombards who, as pagans and Arian Christians, were not on good relations with the Catholic church in Rome.
Aside from Æthelberht's granting of freedom of worship to his wife, the choice of Kent was probably dictated by a number of other factors. Kent was the dominant power in southeastern Britain. Since the eclipse of King Ceawlin of Wessex in 592, Æthelberht was the leading Anglo-Saxon ruler; Bede refers to Æthelberht as having imperium (overlordship) south of the River Humber. Trade between the Franks and Æthelberht's kingdom was well established, and the language barrier between the two regions was apparently only a minor obstacle, as the interpreters for the mission came from the Franks. Lastly, Kent's proximity to the Franks allowed support from a Christian area. There is some evidence, including Gregory's letters to Frankish kings in support of the mission, that some of the Franks felt that they had a claim to overlordship over some of the southern British kingdoms at this time. The presence of a Frankish bishop could also have lent credence to claims of overlordship, if Bertha's Bishop Liudhard was felt to be acting as a representative of the Frankish church and not merely as a spiritual advisor to the queen. Frankish influence was not merely political; archaeological remains attest to a cultural influence as well.
In 595, Gregory chose Augustine, who was the prior of the Abbey of St Andrew's in Rome, to head the mission to Kent. The pope selected monks to accompany Augustine and sought support from the Frankish royalty and clergy in a series of letters, of which some copies survive in Rome. He wrote to King Theuderic II of Burgundy and to King Theudebert II of Austrasia, as well as their grandmother Brunhild, seeking aid for the mission. Gregory thanked King Chlothar II of Neustria for aiding Augustine. Besides hospitality, the Frankish bishops and kings provided interpreters and Frankish priests to accompany the mission. By soliciting help from the Frankish kings and bishops, Gregory helped to assure a friendly reception for Augustine in Kent, as Æthelbert was unlikely to mistreat a mission which visibly had the support of his wife's relatives and people. Moreover, the Franks appreciated the chance to participate in mission that would extend their influence in Kent. Chlothar, in particular, needed a friendly realm across the Channel to help guard his kingdom's flanks against his fellow Frankish kings.
Sources make no mention of why Pope Gregory chose a monk to head the mission. Pope Gregory once wrote to Æthelberht complimenting Augustine's knowledge of the Bible, so Augustine was evidently well educated. Other qualifications included administrative ability, for Gregory was the abbot of St Andrews as well as being pope, which left the day-to-day running of the abbey to Augustine, the prior.