The story has a special historical interest, because it shows how very vague were the boundaries and the occupancies of the little wandering chieftains of this period. It need hardly be pointed out that no regular division into shires can have existed so early, and, as we have already insisted, the Thames itself was not a permanent boundary between any two definable societies, yet those who regard the Anglo-Saxon Chronicle as historical would show one Penda had appeared a few years before as the chief of a group of men with a new name, the Mercians--probably a loose agglomeration of tribes occupying the middle strip of England; a group whose dialect and measures of land are, perhaps, the ancestors of the modern Midland dialect and most of our measures. Cynegil's baptism could not have taken place in territory controlled by Penda, for he was the champion of all the Anti-Christian forces of the time, and though he had just defeated the West Saxons, and (according to a later legend) pushed back their boundary to the line of the Thames, his action, like that of all the little kings of the barbaric age in Britain, can have been no more than a march with a few thousands, a battle, and a retreat. In a word, the true and verifiable story of Cynegil's baptism is one of the many valuable instances which help to prove the unreliability of that part of the early Chronicle which does not deal with ecclesiastical affairs. The priest who received Cynegil into the Church was one Birinus, an Italian, and perhaps a Milanese; he appears, from his first presence in Dorchester, to have fixed the seat of a bishopric in that village. His reasons for choosing the spot are as impossible to discover as are the origins of any other of the characteristics of the place. It was, in any case, as were so many of the sees of the Dark Ages, a frontier see--a sort of ecclesiastical fortress, pushed out to the very limits of the occupation of the enemy. Whether Dorchester continued to be a bishopric from this moment onwards we cannot tell; but no less than three hundred years afterwards--in the tenth century--it appears again, and this time as the centre of the gigantic diocese which stretched throughout the whole of Middle England and right up to the Humber. The Conquest came, the diocese was cut up just afterwards, and the seat of the bishop finally removed from the village to Lincoln, and with the Conquest the importance of Dorchester as a fortified position, an importance which it had held for untold centuries, began to decline in favour of Oxford. The artificial chain of fortifications up the Thames Valley, which had their origin under William the Conqueror, will call our attention to many other spots besides Oxford as these pages proceed, but it is interesting at this moment to consider Oxford in its early military aspect, when it succeeded Dorchester, and came forward as the chief stronghold of the upper Thames Valley above Wallingford.