The power of AEthelberht seems to have declined with old age, and though the Essex men still owned his supremacy, the English tribes of Mid-Britain shook it off. So strong however had the instinct of union now become, that we hear nothing of any return to their old isolation. Mercians and Southumbrians, Middle-English and South-English now owned the lordship of the East-English King Raedwald. The shelter given by Raedwald to AElla's son Eadwine served as a pretext for a Northumbrian attack. Fortune however deserted AEthelfrith, and a snatch of northern song still tells of the day when the river Idle by Retford saw his defeat and fall. But the greatness of Northumbria survived its king. In 617 Eadwine was welcomed back by his own men of Deira; and his conquest of Bernicia maintained that union of the two realms which the Bernician conquest of Deira had first brought about. The greatness of Northumbria now reached its height. Within his own dominions, Eadwine displayed a genius for civil government which shows how utterly the mere age of conquest had passed away. With him began the English proverb so often applied to after kings: "A woman with her babe might walk scatheless from sea to sea in Eadwine's day." Peaceful communication revived along the deserted highways; the springs by the roadside were marked with stakes, and a cup of brass set beside each for the traveller's refreshment. Some faint traditions of the Roman past may have flung their glory round this new "Empire of the English"; a royal standard of purple and gold floated before Eadwine as he rode through the villages; a feather tuft attached to a spear, the Roman tufa, preceded him as he walked through the streets. The Northumbrian king became in fact supreme over Britain as no king of English blood had been before. Northward his frontier reached to the Firth of Forth, and here, if we trust tradition, Eadwine founded a city which bore his name, Edinburgh, Eadwine's burgh. To the west his arms crushed the long resistance of Elmet, the district about Leeds; he was master of Chester, and the fleet he equipped there subdued the isles of Anglesea and Man. South of the Humber he was owned as overlord by the five English states of Mid-Britain. The West-Saxons remained awhile independent. But revolt and slaughter had fatally broken their power when Eadwine attacked them. A story preserved by Baeda tells something of the fierceness of the struggle which ended in the subjection of the south to the overlordship of Northumbria. In an Easter-court which he held in his royal city by the river Derwent, Eadwine gave audience to Eumer, an envoy of Wessex, who brought a message from its king. In the midst of the conference Eumer started to his feet, drew a dagger from his robe, and rushed on the Northumbrian sovereign. Lilla, one of the king's war-band, threw himself between Eadwine and his assassin; but so furious was the stroke that even through Lilla's body the dagger still reached its aim.