ruled by Eirik Hákonarson as King Svein's vassal. The Jarls Eirik and Svein proved strong, competent rulers, and their reign was prosperous. Most sources say that they adopted Christianity but allowed the people religious freedom, leading to a backlash against Christianity which undid much of Olaf Tryggvason's missionary work. Religion Sweyn apparently recruited priests and bishops from England, in preference to the Archbishopric of Bremen. In part, this reflected the fact that there were numerous Christian priests of Danish origin in the Danelaw, while Sweyn had few personal connections to Germany. However, Sweyn's preference for the English church may also have had a political motive, because German bishops were an integral part of the state. It has been suggested that Sweyn was seeking to pre-empt any diminution of his independence by German leaders. This may have been a reason for Adam of Bremen's apparent hostility in his accounts of Sweyn; by accentuating English ecclesiastical influence in his kingdom, Sweyn was effectively spurning the Archbishop of Bremen. Invasions of England The "Chronicle of John of Wallingford" (c. 1225–1250) records Sweyn's involvement in raids against England during 1002–1005, 1006–1007 and 1009–1012 to avenge the St. Brice's Day massacre of England's Danish inhabitants in November 1002. According to Ashley (1998), Sweyn's invasion was partly motivated by the massacre of Danes in England ordered by Æthelred the Unready in 1002, in which his sister and brother-in-law are said to have been killed, but Lund (2001) argues that the main motivation for the raids was more likely the prospect of revenue. At the outset of the invasions, Sweyn negotiated an agreement with Duke Richard II of Normandy whereby the Danes gained permission to sell their spoils of war in Normandy. Sweyn campaigned in Wessex and East Anglia in 1003–1004, but a famine forced him to return to Denmark in 1005. Further raids took place in 1006–1007, and in 1009–1012 Thorkell the Tall led a Viking invasion into England. Simon Keynes regards it as uncertain whether Sweyn supported these invasions, but "whatever the case, he was quick to exploit the disruption caused by the activities of Thorkell's army". Sweyn acquired massive sums of Danegeld through the raids. In 1013, he is reported to have personally led his forces in a full-scale invasion of England. The medieval Peterborough Chronicle (part of the Anglo-Saxon Chronicle) states: before the month of August came king Sweyn with his fleet to