Eastward from Chollerford is the little church of St. Oswald, standing where the battle of Heavenfield took place. When Penda of Mercia, and the British Prince Cadwallon, were warring against Northumbria, the greatest Northumbrian King, Edwin, was defeated and slain by them; and on their return to the attack, Ethelfrith’s eldest son, called back from exile to take the vacant throne, and rule in his father’s seat of Bamburgh, also fell before their fierce onslaught. His brother Oswald now took command of the Bernicians and prepared to lead them against the foe. Oswald posted his men in a strong position on the north side of the great Wall; and, setting up a huge cross of wood, called upon all his followers to bow before the God of whom he had learnt during his exile in Iona, and to pray to Him for victory. His army obeyed, and, in the battle which followed, Oswald’s forces were completely victorious. The Mercians, and their allies, the western Britons, were routed, and driven out of Bernicia, and Cadwallon was pursued as far as the Denise Burn, and there slain. The Denise Burn is supposed to have been the Rowley Burn, which flows into the Devil’s Water, on whose banks stands Dilsten Castle. Some time later, on the spot where Oswald’s Cross had stood, a church was erected and dedicated to the royal Saint. It was served from Hexham Abbey. After passing Wall, which, however, is not quite so near the Roman Wall as Chollerford is, we come to the pretty village of Warden, nestling beneath the woods of Warden Hill; and here, just above Hexham, the North Tyne unites with its sister river in the rich meadow lands which lie near the old town. The South Tyne has journeyed from Cross Fell, where it takes its rise, northward through a corner of Cumberland, past Garrygill and Alston, until it enters Northumberland where the Ayle Burn on the one hand, and the Gilderdale Burn on the other, flow into it. Here is Whitley Castle, where was a small Roman station called Alio, and Kirkhaugh Church, charmingly placed on the bank of the river, which continues its course northward past Slaggyford, Knaresdale, Eals, and Lambley, till it flows past the fine Castle of Featherstone, and the ruins of Bellister, where it turns eastward to Haltwhistle. The little streams which enter the South Tyne up to this point flow through wild and romantic glens, two of them owning the Celtic names of _Glen Cune_ and _Glen Dhu_.