It was at this time, when Alfred was growing up to manhood, that the troubles in Northumbria of which we have already given an account took place. The reign of Ælla, and his horrible death at the hands of Lodbrog’s sons, was followed by the advance of the pagan army into Mercia, and it was here that Alfred came for the first, time face to face with the enemy against whom much of his life was to be spent in conflict. Burhred, King of the Mercians, sent to Ethelred and Alfred to beg their assistance against the pagan army. They immediately responded by marching to Nottingham with a large host, all eager to fight the Danes; but the pagans, shut up safely within the walls of the castle, declined to fight, and in the end a peace was patched up between the Danes and the Mercians, and the two Wessex princes returned home without a battle. It was not long, however, before the army was needed again; for, three years later, in the year 871, when Alfred was twenty-three years of age, “the army of the Danes of hateful memory,” as Asser calls it, entered Wessex itself, coming up from East Anglia, where they had wintered. After attacking the then royal city of Reading, on the Thames, they entrenched themselves on the right of the town. Ethelred was not able to come up with them at so short notice, but the Earl of Berkshire, gathering a large army, attacked them in the rear at Englefield Green, and defeated them, many of them taking to flight. Four days afterwards the two princes of Wessex, Ethelred and Alfred, came up, and soon cut to pieces the Danes that were defending the city outside; but those Danes who had shut themselves in the city sallied out of the gates, and after a long and hot encounter the army of Wessex fled, the brave Earl of Berkshire being among the slain.