Just at this moment, when the country was most divided, the dreaded pagan army advanced over the mouth of the Humber from the south-east into Yorkshire. In this emergency all classes united for the common defence, and we find Osbert, the dethroned king, nobly marching side by side with his rival to meet the Northmen. Hearing that a great army was approaching, the Northmen shut themselves up within the walls of York, and attempted to defend themselves behind them. The Northumbrians succeeded in making a breach in the walls and entering the town; but, inspired by fear and necessity, the pagans made a fierce sally, cutting down their foes on all sides, inside and outside the walls alike. The city was set on fire, those who escaped making peace with the enemy. From that time onward the Northmen were seldom absent from Northumbria. York became one of their chief headquarters, and the constant succession of Norse ships along the coast gradually brought a considerable influx of Norse inhabitants to that part of England. It became, in fact, a viking kingdom, under the sons of Ragnar Lodbrog, whose story we have now to tell. This was in the time of the first Ethelred, when Alfred the Great was about twenty years of age. Ethelred was too much occupied in warring with the pagans in the South of England to be able to give any aid to the Northumbrians. Chapter II The Saga of Ragnar Lodbrog, or “Hairy-breeks” According to the Danish and Norse accounts, the leader of the armies of the Northmen on the occasion we have just referred to was the famous Ragnar Lodbrog, one of the earliest and most terrible of the Northern vikings. The story of Ragnar stands just on the borderland between mythology and history, and it is difficult to tell how much of it is true, but in some of its main outlines it accords with the rather scanty information we get at this time from the English annals. An old tradition relates how Ragnar got his title of Lodbrog, or “Hairy-breeks.”