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 Conailli, the Ui Tortain, and the Ui Meith were captured or killed at the Battle of Inbher Boinne. In 1035, he plundered the celebrated stone church of Ardbraccan in Meath, burned 200 men inside, and carried another 200 off into captivity. (In revenge, the church at Swords was plundered and burned by Conchobhar Ua Maeleachlainn, who took away cattle and captives.)