Cashel in the Great Frost
Archived: 27 October 2026
Abstract
In 941, exceptional frost froze waterways, allowing raiders to plunder Inis Mochta and disrupting ordinary travel and supplies. Muirchertach mac Néill, king of Ailech, campaigned through Mide, Uí Fhailge, Osraige and the Déisi, securing Cellachán of Cashel’s submission to Donnchad Donn of Tara. The campaign demonstrated northern power but did not establish lasting conquest. Cellachán had fought the Déisi, while Muirchertach also raided the Hebrides by fleet. Amlaíb mac Gofraid, Dublin-linked ruler of York and Mercia, died in Lothian. Brian Bóruma was notably also born. Later poetry magnified Muirchertach’s circuit, but contemporary annals depict a politically fragmented Irish Sea world.