In 951, while Amlaíb was in Britain his brother Gofraid died in Dublin of disease.Downham, Viking Kings, pp. 47 & 254; Hudson, "Óláf Sihtricson". Congalach's rival Ruaidrí was also dead, leaving Amlaíb's former ally as undisputed High King and thus a serious threat to Dublin and the south-eastern Irish kingdom of Leinster. This threat was perhaps what led to Congalach's death in an ambush at Dún Ailinne (modern County Kildare) or at Tech Guigenn in the region of the River Liffey while collecting tribute in Leinster in 956.Downham, Viking Kings, pp. 48 & 241; Hudson, "Óláf Sihtricson". The main beneficiary was the brother of Amlaíb's new wife Dúnflaith, Domnall ua Néill, who became the next High King of Ireland. The marriage linked Amlaíb not only to the northern Uí Néill kindred of Cenél nEógain, but also to the southern Clann Cholmáin as he was now stepfather to Dúnflaith's young son Máel Sechnaill mac Domnaill.Hudson, "Domnall ua Néill"; Hudson, Viking Pirates, page numbers needed.
