Looking out to sea in Proteus, Stephen casts his thoughts back eleven centuries, to the time of the first Viking invasions of Ireland: "Galleys of the Lochlanns ran here to beach, in quest of prey, their bloodbeaked prows riding low on a molten pewter surf." Lochlann (land of the lochs, i.e. the fjords of Norway), a Gaelic name preserved to the present day in both Ireland and Scotland, refers to the first Viking raiders and settlers of Ireland, in the last decade of the 8th century and the first decades of the 9th. At about the same time, other invaders from what is now Denmark began settling Britain, and in 853 these new Scandinavians arrived in Ireland. Stephen thinks of them in the next breath: "Dane vikings, torcs of tomahawks aglitter on their breasts when Malachi wore the collar of gold."
In a lecture titled "Ireland, Island of Saints and Sages" (1907), Joyce observed that "Anyone who reads the history of the three centuries that precede the coming of the English must have a strong stomach, because the internecine strife, and the conflicts with the Danes and the Norwegians, the black foreigners and the white foreigners, as they were called, follow each other so continuously and ferociously that they make this entire era a veritable slaughterhouse. The Danes occupied all the principal ports on the east coast of the island and established a kingdom at Dublin."
The invaders possessed the most formidable warships of the time: light, slender, flexible, and shallow-drafting galleys that could cut the seas swiftly, venture up rivers, and land on beaches. As Gifford notes, the Danes also had "metal bodyarmor (coats of mail and helmets with visors)" that the Gaels could not match. He speculates that "torcs of tomahawks aglitter on their breasts" refers to a device of reversed battle-axes that the Danes often wore on top of their mail coats.