at Áth Senaig in 738. This fight (known as the Battle of the Groans) is described at length in the Irish annals. Áed was slain in single combat with Áed Allán and his supposed co-ruler Bran Bec also died there. The Annals of Ulster say:

And men say that so many fell in this great battle that we find no comparable slaughter in a single onslaught and fierce conflict throughout all preceding ages.