The Engle had probably been settling for years along the coast of Northumbria and in the great district which was cut off from the rest of Britain by the Wash and the Fens, the later East Anglia.  But it was not till the moment we have reached that the line of defences which had hitherto held the invaders at bay was turned by their appearance in the Humber and the Trent.  This great river line led like a highway into the heart of Britain; and civil strife seems to have broken the strength of British resistance.  But of the incidents of this final struggle we know nothing.  One part of the English force marched from the Humber over the Yorkshire wolds to found what was called the kingdom of the Deirans.

Under the empire political power had centred in the district between the Humber and the Roman wall; York was the capital of Roman Britain; villas of rich land-owners studded the valley of the Ouse; and the bulk of the garrison maintained in the island lay camped along its northern border.  But no record tells us how Yorkshire was won, or how the Engle made themselves masters of the uplands about Lincoln.  It is only by their later settlements that we follow their march into the heart of Britain.  Seizing the valley of the Don and whatever breaks there were in the woodland that then filled the space between the Humber and the Trent, the Engle followed the curve of the latter river, and struck along the line of its tributary the Soar.  Here round the Roman Ratae, the predecessor of our Leicester, settled a tribe known as the Middle English, while a small body pushed farther southward, and under the name of “South Engle” occupied the ooelitic upland that forms our present Northamptonshire.

But the mass of the invaders seem to have held to the line of the Trent and to have pushed westward to its head-waters.  Repton, Lichfield, and Tamworth mark the country of these western Englishmen, whose older name was soon lost in that of Mercians, or Men of the March.  Their settlement was in fact a new march or borderland between conqueror and conquered; for here the impenetrable fastness of the Peak, the mass of Cannock Chase, and the broken country of Staffordshire enabled the Briton to make a fresh and desperate stand.

It was probably this conquest of Mid-Britain by the Engle that roused the West Saxons to a new advance.  For thirty years they had rested inactive within the limits of the Gwent, but in 552 their capture of the hill fort of Old Sarum threw open the reaches of the Wiltshire downs, and a march of King Cuthwulf on the Thames made them masters in 571 of the districts which now form Oxfordshire and Berkshire.