James Gray, Sutherland and Caithness in Saga-Time…
“ In the reign of the great king Constantine III, between the years 900 and 942, the Danes again gave trouble. In 903 the Irish Danes ravaged Alban,11 as Scotland north of the Forth was then called, for a whole year; in 918 Constantine and his ally, Eldred of Lothian, were defeated by another expedition of these invaders; and in 934 Athelstan and his Saxons burst into Strathclyde and Forfar, the heart of Constantine's kingdom, and the Saxon fleet was sent up even to the shores of Caithness, as a naval demonstration intended to brave the Norse, who had joined Constantine, on their own element. ”
