 Sigtrygg 's fortunes improved in the 1030s . In 1030 , he allied with the King of England , Cnut , and together their fleets raided Wales . A Dublin colony was established in Gwynedd , and for the following years Sigtrygg was at the height of his power . In 1032 , without allies , Sigtrygg won a victory on the Boyne estuary of a type previously unseen by his dynasty for two decades , against a coalition of three kingdoms : over 300 members of the <unk> , the Ui <unk> , and the Ui <unk> were captured or killed at the Battle of <unk> <unk> . In 1035 , he plundered the celebrated stone church <unk> in Meath , burned 200 men inside , and carried another 200 off into captivity . ( In revenge , the church at Swords was plundered and burned by <unk> Ua <unk> , who took away cattle and captives . ) 
