In the war with the Danes during the reign of Ethelred II., Berkshire was again laid waste by fire and sword, and the barbarous invaders burnt Reading, Wallingford, and other places in 1006. They destroyed, too, with ruthless hand the numerous churches and monasteries, which since the conversion of the Saxons to Christianity, had been erected in our towns and hamlets. This conversion was accomplished by the preaching of Berin or Birinus, who, with a company of faithful monks, arrived in Berkshire about 636 A.D. He was received by King Kynegils, Oswald of Northumbria, his son-in-law, and other princes at Churn Knob, and convinced his hearers of the truth of Christianity. The King and his court were baptised at Dorchester, which became an important centre of missionary enterprise. The earliest monastic house was the famous abbey of Abingdon, founded by Heane, its first prior, and nephew of Cissa, Viceroy of Kentwine, who was a great benefactor to the monastery. Here also Heane's sister founded a nunnery dedicated to St. Helen, which was removed to Wytham. The abbey, in spite of being burned by the Danes, became very rich and prosperous. At Reading, Elfreda founded a nunnery in expiation of the murder of her step-son, and almost every village had its parish church. In the time of the Norman Conquest there were as many as 1,700. At Sonning there was a bishop's palace, but although Leland speaks of the Bishops of Sonning, it was never an episcopal seat. Soon the peaceful hamlets of Saxon folk were rudely disturbed by the advent of the Norman invaders, and Saxon writers lament over the sadness of the times, when English lands were bestowed upon the followers and favourites of the Conqueror, who reared their mighty strongholds everywhere, "filled with devils and evil men," who plundered the English, confined them in dungeons, and were guilty of every kind of cruelty and crime. At Wallingford, William received the submission of Archbishop Stigand and the principal barons before he marched to London. There arose the strong castle, built by Robert D'Oyly, and others were erected at Windsor, Reading, Newbury, and later at Farringdon, Brightwell, and Donnington. The history of the castles at Wallingford and Windsor will be recorded in this volume; Donnington endured an exciting siege during the Civil Wars; the others were speedily destroyed.