There were supposedly Viking warriors that were able to achieve a state of fury and frenzy that made them “go berserk” during fights or in battle. However, whether this was merely part of the aura and myth surrounding Scandinavian/norse raiders at the time – or an actual ability of berserking is still not confirmed.
If berserking was a state, how was it attained? Theories include the Vikings being able to work themselves into this state of combat readiness, or was it consumption of alcohol or other drug, or perhaps some form of witchcraft? These ideas are still being investigated. However interestingly then there is evidence that starting in the early 11th century berserking was forbidden and outlawed.