988 - Varangian guard founded at Constantinople

The Berserker
Greece
The Varangian guard was founded at Constantinople by The Byzantine emperor Basil II. The Rus leader Vladimir sent 6,000 men to Basil II.
It was recruited from Norsemen from Russia, as a personal bodyguard. The term Varangian comes from the Norse var, meaning “pledge,” and denotes one of a band of men who pledged themselves to work together for a profit. Usually this meant in trade, but the oath of loyalty to each other certainly had more than commercial meaning, for they were bound to fight for each others safety as members of a merchant band.
Basil 2(Bulgar slayer)

Basil made use of his new soldiers immediately, taking them with him on an expedition into Bulgaria, where the Varangians so distinguished themselves that Basil separated them from the remainder of the army in order to give them a larger share of the loot and they also served under his command in Anatolia and Georgia.

The main function was to act as guard at the entrance to his bedchamber and violently or otherwise protect him but Varangians might also acted as prison guards and probably as torturers. The "axe-bearers” is a common description of  the Varangians, Harald Sigurdsson, also known as Harald Hardrada was the most famous Varangian.

City walls of Constantinople
Ukraine
Vladimir, prince of Kiev converted to Orthodox Christianity and married Anna, sister of Byzantine emperor Basil II.
Ireland
Dublin, Ireland was founded
Denmark
The city of Odense, Denmark was founded
Wales
The Vikings attacked the Church of St. David at Menevia, as well as the monastic houses of Llanbadarn Fawr near Aberystwyrth, (modern St. Dogmaels) near Cardigan, Llancarfan near Glamorgan, and Llanilltrud, also near Glamorgan.