THE VIKING BERSERKER

IN OLD NORSE SOURCES, VIKING BERSERKERS WERE WARRIORS WHO FOUGHT IN A TRANCE-LIKE FURY, THAT LATER GAVE RISE TO THE ENGLISH WORD, “BERSERK”.
The name likely means “bear-shirt” (comparable in Middle English to the word “serk”, that means “shirt”), with warriors traditional going into battle without armour, instead wearing bear or wolf pelts.

Some scholars argue that the origins of the berserker can be found during the Roman period, such as the Germanic social structures described by the Roman historian, Tacitus, or in scene 36 on Trajan’s column in Rome, which depicts tribal warriors wearing bear hoods and wolf hoods.

One of the earliest written texts describing berserkers is the Hrafnsmál, a 9th century fragmentary skaldic poem, written by Norwegian skald, Þorbjörn Hornklofi:

‘‘They [the ships] were loaded with men and white shields, western spears and Frankish swords. Berserks bellowed; battle was under way for them; wolf-skins [berserks] howled and brandished iron spears.’

‘‘They are called wolf-skins, who bear bloody shields in combat; they redden spears when they come to war; there [at Haraldr’s court] they are seated together. There, I believe, he, the sovereign wise in understanding, may entrust himself to men of courage alone, those who hew into a shield.’’

To “go berserk” was to “hamask”, which translates as “change form”, in this case, as with the sense “enter a state of wild fury”, or literally to shapeshift into a bear’s form. They were portrayed as indestructible in the sagas, immune to most fatal woes and possessing a superhuman strength.

More:
https://www.heritagedaily.com/2022/12/the-viking-berserker/145605