Augustine was an Italian monk, who probably died in 604 He was prior of St. Andrew's monastery in Rome and was chosen by Pope Gregory the Great to lead a mission to the southern English. The work of the mission is known from the register books of Pope Gregory1s letters, and from the account written by the Northumbrian scholar Bede completed in 731 and based on Kentish sources. These texts have been extensively examined in the last 60 years, so that many statements are now controversial.

Augustine and a party of 40 monks set out from Rome in 596. Letters sent by Gregory in July that year reveal that they had reached the island monastery of Lerins near Cannes, and gone on to Aix and Aries in Provence. Being discouraged, they had sent Augustine back to Rome to ask Gregory to release them from their obligation. This Gregory refused to do. He sent Augustine out again in July 596, armed with letters asking help for the party from kings and bishops along their route. Augustine was made abbot, so that he might better command the monks' obedience. They went up the Rhone valley to Vienne, Lyons and Autun. After this the route is uncertain - they may have gone to Tours, but they probably sailed to England from near Etaples, from a port called Quentavic. At some time between July 596 and September 597, Augustine was consecrated as bishop, somewhere in France. Bede says he returned to France for this purpose; modern scholars suppose he was consecrated on his way to England.

The exact date of arrival is not known, though the spring 597 seems most likely. Bede describes the party's arrival, and their meeting with King Ethelbert of Kent near Ebbsfleet. Ethelbert was a powerful king who exercised overlordship over the other English kings from his base at Canterbury, a former Roman city. He was married to Bertha, a Frankish princess whose father was Charibert, king of Paris. She was Christian, with her own chaplain, Bishop Luidard. They used the small church of St. Martin outside the city of Canterbury, where part of the walling within the present church remains from the 590s or earlier.

Ethelbert allowed Augustine and his monks to lodge in Canterbury and preach. They too used the church at St. Martin's. They made converts, including Ethelbert, who was said to have been baptised at Whitsun (June) 597. The king's conversion enabled the missioners to preach over a wider area, and to build and restore churches. Ethelbert gave Augustine a church for restoration said to date back to the Roman city of Canterbury. The Cathedral was founded there, with lodging beside it for Augustine and his entourage. No sign of a church on a Roman alignment was seen in the excavations of 1993, though the earliest church discovered on the Cathedral site may date to the early 7th century. Ethelbert also founded in 598 a monastery for the monk-missioners, dedicated to St. Peter and St. Paul, which was also to provide a burial place for the archbishops and the kings of Kent, outside the city as Roman custom required. Foundations of the church of 598, later dedicated to St. Augustine, have been excavated on this site.

By July 598 Pope Gregory had received news of the success of the mission. Further missioners were sent out in July 601, of whom the leaders were Mellitus, Justus, Paulinus and Rufinianus. They brought with them plate and vestments for church use, relics and books, one of which may be the 6th century Italian gospel book now of Corpus Christi College, Cambridge, on which each archbishop of Canterbury takes his oath at his enthronement. In 604 two bishoprics were founded, Rochester, where Justus became bishop, and London, the seat of Mellitus. There had been bishops in London under the Roman Empire, but the barbarian invaders broke the succession. Laurence, one of the original missioners, was consecrated by Augustine as his successor, perhaps in 604. Augustine died on 26th May, but there seems no record now of which year he died, probably 604 or 605.

Though the mission was successful in Kent for some years, there was a reaction after Ethelbert's death in 616. Similarly the Christians in London suffered persecution and failure. Mellitus and Justus returned to France for a time, until pagan opposition was weakened, Possibly as a result of this setback, London never became the headquarters of the southern archbishopric as Gregory had intended, comparable to York in the North. The archbishopric remained at Canterbury. Bede related how Augustine tried to enlist the help of Welsh Christians for mission among the Anglo-Saxons, He met them on the English side of the Welsh border county. After a long dispute about differing Christian customs, they were impressed by Augustine's healing of a blind man, but at a second meeting they thought him proud and refused to co-operate. For a variety of reasons, the teaching of St Augustine's mission did not spread far in the early 7th century, but it provided a firm base for later missionary activities for the conversion of the Anglo-Saxons.