Irreplaceable special force

Since the times of the Roman Empire, praetorian guard very often played an infamous role of replacing one ruler with the other. Especially, if the new guy promised to pay the praetorians more. This practice survived even after Roman Empire split in two and new Byzantine Empire was created.

In 976 Bazil II became the ruler of the empire. He had the utmost distrust for his native guardsmen, whose loyalties shifted all the time, so he was seeking the solution to protect himself and avoid fatal consequences. And he found it: he hired Vikings, mostly of Swedish origin, to become his personal bodyguards. This new force became known as the Varangian Guard. As the years went by, new recruits from Sweden, Denmark, and Norway kept a predominantly Scandinavian cast to Varangian Guard up until the late 11th century. That kind of "employment" became so popular in Scandinavia, that special medieval law was created there stating that no one could inherit the estate of a recruit who was staying in Byzantium.

Over the years, Varangian Guard proved itself to be an irreplaceable special force of Byzantine emperors. And they had one of the greatest and unique perks for their service. When the Byzantine Emperor died, the Varangians had the unique right of running to the imperial treasury and taking as much gold and as many gems as they could carry. This privilege known in Old Norse as "palace pillaging" enabled many Varangians to return home as wealthy men. And, in return, it encouraged even more Vikings to enlist in the Varangian Guard.