The Varangian Guards were Viking mercenaries who operated far beyond their native shores as an elite force within the Byzantine Armies. Descendants from a legendary line of warriors, the Varangian Guard was formed after a group of Viking mercenaries made a major contribution to the Byzantine Emperor Basil II's victory over rebel forces in 988 AD. These 5,000 men were then retained as Basil's personal guard and would provide loyal service to many successive occupants of the imperial throne.

Commonly referred to as 'foreigners' (Etaireia), they were nonetheless absorbed into a new...