Hudson argues that Tryggvason's return to Norway in 994 coincided with the temporary expulsion of Sigtrygg from Dublin by his rival Ivar of Waterford. Ivar may have already ruled there from 989 until forced out by Sigtrygg in 993. Much depends on the interpretation. Either way, Sigtrygg was back within a year. In 995, he and his nephew, Muirchertach Ua Congalaich, attacked the church at Donaghpatrick in County Meath. In retaliation, Máel Sechnaill entered Dublin and took the ring of Thor and the sword of Carlus. Sigtrygg then attacked Kells and Clonard in 997. In 998, Máel Sechnaill and the King of Munster, Brian Boru, forced Sigtrygg to recognise their lordship by giving hostages.