Powerful as Æthelfrith was, he was jealous of young Eadwine, a son of his father's rival, Ælla of Deira. For some years Eadwine had been in hiding, at one time with Welsh princes, at another time with English kings. In 617 he took refuge with Rædwald, the king of the East Angles. Æthelfrith demanded the surrender of the fugitive. Rædwald hesitated, but at last refused. Æthelfrith attacked him, but was defeated and slain near the river Idle, at some point near Retford. Eadwine the Deiran then became king over the united North-humberland in the place of Æthelfrith the Bernician, whose sons fled for safety to the Picts beyond the Forth. Eadwine completed and consolidated the conquests of his predecessors. He placed a fortress, named after himself Eadwinesburh, or Edinburgh, on a rocky height near the Forth, to guard his land against a fresh irruption of Scots and Picts, such as that which had been turned back at Degsastan. He conquered from the Kymry Loidis and Elmet, and he launched a fleet at Chester which added to his dominions the Isle of Man and the greater island which was henceforth known as Anglesea, the island of the Angles. Eadwine assumed unwonted state. Wherever he went a standard was borne before him, as well as a spear decorated with a tuft of feathers, the ancient sign of Roman authority. It has been thought by some that his meaning was that he, rather than any Welshman, was the true Gwledig, the successor of the Duke of the Britains (Dux Britanniarum), and that the name of Bretwalda, or ruler of the Britons, which he is said to have borne, was only a translation of the Welsh Gwledig. It is true that the title of Bretwalda is given to other powerful kings before and after Eadwine, some of whom were in no sense rulers over Britons; but it is possible that it was taken to signify a ruler over a large part of Britain, though the men over whom he ruled were English, and not Britons.
The long range of barren hills which separated Æthelfrith's kingdom from the Kymry made it difficult for either side to strike a serious blow at the other. In the extreme north, where a low valley joins the Firths of Clyde and Forth, it was easier for them to meet. Here the Kymry found an ally outside their own borders. Towards the end of the fifth century a colony of Irish Scots had driven out the Picts from the modern Argyle. In 603 their king, Aedan, bringing with him a vast army, in which Picts and the Kymry appear to have taken part, invaded the northern part of Æthelfrith's country. Æthelfrith defeated him at Degsastan, which was probably Dawstone, near Jedburgh. 'From that time no king of the Scots durst come into Britain to make war upon the English.'
Having freed himself from the Scots in the north, Æthelfrith turned upon the Kymry. After a succession of struggles of which no record remains, he forced his way in 613 to the western sea near Chester. The Kymry had brought with them the 2,000 monks of their great monastery Bangor-iscoed, to pray for victory whilst their warriors were engaged in battle. Æthelfrith bade his men to slay them all. 'Whether they bear arms or no,' he said, 'they fight against us when they cry against us to their God.' The monks were slain to a man. Their countrymen were routed, and Chester fell into the hands of the English. The capture of Chester split the Kymric kingdom in two, as the battle of Deorham thirty-five years before had split that kingdom off from the West Welsh of the south-western peninsula. The Southern Kymry, in what is now called Wales, could no longer give help to the Northern Kymry between the Clyde and the Ribble, who grouped themselves into the kingdom of Strathclyde, the capital of which was Alcluyd, the modern Dumbarton. Three weak Celtic states, unable to assist one another, would not long be able to resist their invaders.
In 593, four years before the landing of Augustine, Æthelric was succeeded by his son Æthelfrith. Æthelfrith began a fresh struggle with the Welsh. We know little of the internal history of the Welsh population, but what we do know shows that towards the end of the sixth century there was an improvement in their religious and political existence. The monasteries were thronged, especially the great monastery of Bangor-iscoed, in the modern Flintshire, which contained 2,000 monks. St. David and other bishops gave examples of piety. In fighting against Æthelfrith the warriors of the Britons were fighting for their last chance of independence. They still held the west from the Clyde to the Channel. Unhappily for them, the Severn, the Dee, and the Solway Firth divided their land into four portions, and if an enemy coming from the east could seize upon the heads of the inlets into which those rivers flowed he could prevent the defenders of the west from aiding one another. Already in 577, by the victory of Deorham, the West Saxons had seized on the mouth of the Severn, and had split off the West Welsh of the south-western peninsula. Æthelfrith had to do with the Kymry, whose territories stretched from the Bristol Channel to the Clyde, and who held an outlying wedge of land then known as Loidis and Elmet, which now together form the West Riding of Yorkshire.
In 616 Æthelberht died. The over-lordship of the kings of Kent ended with him, and Augustine's church, which had largely depended upon his influence, very nearly ended as well. Essex relapsed into heathenism, and it was only by terrifying Æthelberht's son with the vengeance of St. Peter that Lawrence kept him from relapsing also. On the other hand, Rædwald, king of the East Anglians, who succeeded to much of Æthelberht's authority, so far accepted Christianity as to worship Christ amongst his other gods.
Augustine's Church was weak, because it depended on the kings, and had not had time to root itself in the affections of the people. Æthelberht's supremacy was also weak. The greater part of the small states which still existed—Sussex, Kent, Essex, East Anglia, and most of the small kingdoms of central England—were no longer bordered by a Celtic population. For them the war of conquest and defence was at an end. If any one of the kingdoms was to rise to permanent supremacy it must be one of those engaged in strenuous warfare, and as yet strenuous warfare was only carried on with the Welsh. The kingdoms which had the Welsh on their borders were three—Wessex, Mercia, and North-humberland, and neither Wessex nor Mercia was as yet very strong. Wessex was too distracted by conflicts amongst members of the kingly family, and Mercia was as yet too small to be of much account. North-humberland was therefore the first of the three to rise to the foremost place. Till the death of Ælla, the king of Deira, from whose land had been carried off the slave-boys whose faces had charmed Gregory at Rome, Deira and Bernicia had been as separate as Kent and Essex. Then in 588 Æthelric of Bernicia drove out Ælla's son and seized his kingdom of Deira, thus joining the two kingdoms of Deira and Bernicia into one, under the new name of North-humberland.
After a short stay Augustine revisited Gaul and came back as Archbishop of the English. Æthelberht gave to him a ruined church at Canterbury, and that poor church was named Christ Church, and became the mother church of England. From that day the Archbishop's See has been fixed at Canterbury. If Augustine in his character of monk led men by example, in his character of Archbishop he had to organise the Church. With Æthelberht's help he set up a bishopric at Rochester and another in London. London was now again an important trading city, which, though not in Æthelberht's own kingdom of Kent, formed part of the kingdom of Essex, which was dependent on Kent. More than these three Sees Augustine was unable to establish. An attempt to obtain the friendly co-operation of the Welsh bishops broke down because Augustine insisted on their adoption of Roman customs; and Lawrence, who succeeded to the archbishopric after Augustine's death, could do no more than his predecessor had done.
These missionaries were monks as well as preachers. The Christians of those days considered the monastic life to be the highest. In the early days of the Church, when the world was full of vice and cruelty, it seemed hardly possible to live in the world without being dragged down to its wickedness. Men and women, therefore, who wished to keep themselves pure, withdrew to hermitages or monasteries, where they might be removed from temptation, and might fit themselves for heaven by prayer and fasting. In the fifth century Benedict of Nursia had organised in Italy a system of life for the monastery which he governed, and the Benedictine rule, as it was called, was soon accepted in almost all the monasteries of Western Europe. The special feature of this rule was that it encouraged labour as well as prayer. It was a saying of Benedict himself that 'to labour is to pray.' He did not mean that labour was good in itself, but that monks who worked during some hours of the day would guard their minds against evil thoughts better than if they tried to pray all day long. Augustine and his companions were Benedictine monks, and their quietness and contentedness attracted the population amidst which they had settled. The religion of the heathen English was a religion which favoured bravery and endurance, counting the warrior who slaughtered most enemies as most highly favoured by the gods.
The religion of Augustine was one of peace and self-denial. Its symbol was the cross, to be borne in the heart of the believer. The message brought by Augustine was very hard to learn. If Augustine had expected the whole English population to forsake entirely its evil ways and to walk in paths of peace, he would probably have been rejected at once. It was perhaps because he was a monk that he did not expect so much. A monk was accustomed to judge laymen by a lower standard of self-denial than that by which he judged himself. He would, therefore, not ask too much of the new converts. They must forsake the heathen temples and sacrifices, and must give up some particularly evil habits. The rest must be left to time and the example of the monks.
Augustine with his companions landed at Ebbsfleet, in Thanet, where Æthelberht's forefathers had landed nearly a century and a half before. After a while Æthelberht arrived. Singing a litany, and bearing aloft a painting of the Saviour, the missionaries appeared before him. He had already learned from his Christian wife to respect Christians, but he was not prepared to forsake his own religion. He welcomed the new-comers, and told them that they were free to convert those who would willingly accept their doctrine. A place was assigned to them in Canterbury, and they were allowed to use Bertha's church. In the end Æthelberht himself, together with thousands of the Kentish men, received baptism. It was more by their example than by their teaching that Augustine's band won converts. The missionaries lived 'after the model of the primitive Church, giving themselves to frequent prayers, watchings, and fastings; preaching to all who were within their reach, disregarding all worldly things as matters with which they had nothing to do, accepting from those whom they taught just what seemed necessary for livelihood, living themselves altogether in accordance with what they taught, and with hearts prepared to suffer every adversity, or even to die, for that truth which they preached.'