Again, however, the church received a severe check.  Mercia, the youngest and roughest principality, stood out for heathendom.  The western colony was beginning to raise itself into a great power, under its fierce and strong old king Penda, who seems to have consolidated all the petty chieftainships of the Midlands into a single fairly coherent kingdom.  Penda hated Northumbria, which, under Eadwine, had made itself the chief English state:  and he also hated Christianity, which he knew only as a religion fit for Welsh slaves, not for English warriors.  For twenty-two years, therefore, the old heathen king waged an untiring war against Christian Northumbria.  In 633, he allied himself with Cadwalla, the Christian Welsh king of Gwynedd, or North Wales, in a war against Eadwine; an alliance which supplies one more proof that the gulf between Welsh and English was not so wide as it is sometimes represented to be.  The Welsh and Mercian host met the Northumbrians at Heathfield (perhaps Hatfield Chase) and utterly destroyed them.  Eadwine himself and his son Osfrith were slain.  Penda and Cadwalla “fared thence, and undid all Northumbria.”  The country was once more divided into Deira and Bernicia, and two heathen rulers succeeded to the northern kingdom.  Paulinus, taking AEthelburh, the widow of Eadwine, went by sea to Kent, where Honorius, whom he had himself consecrated, received him cordially, and gave him the vacant see of Rochester.  There he remained till his death, and so for a time ended the Christian mission to York.  Penda made the best of his victory by annexing the Southumbrians, the Middle English, and the Lindiswaras, as well as by conquering the Severn Valley from the West Saxons.  Henceforth, Mercia stands forth as one of the three leading Teutonic states in Britain.

CHAPTER X.

ROME AND IONA.

It was not the Roman mission which finally succeeded in converting the North and the Midlands.  That success was due to the Scottish and Pictish Church.  At the end of the sixth century, Columba, an Irish missionary, crossed over to the solitary rock of Iona, where he established an abbey on the Irish model, and quickly evangelised the northern Picts.  From Iona, some generations later, went forth the devoted missionaries who finally converted the northern half of England.

The native churches of the west, cut off from direct intercourse with the main body of Latin Christendom, had retained certain habits which were now regarded by Rome as schismatical.  Chief among these were the date of celebrating Easter, and the uncanonical method of cutting the tonsure in a crescent instead of a circle.  Augustine, shortly after his arrival, endeavoured to obtain unity between the two churches on these matters of discipline, to which great importance was attached as tests of submission to the Latin rule.  He obtained from AEthelberht a safe-conduct through the heathen West-Saxon territories as far as what