From Wiki:
“Berserkers (or berserks) were Norse warriors who are reported in the Old Norse literature to have fought in a nearly uncontrollable, trance-like fury, a characteristic which later gave rise to the English word berserk. Berserkers are attested in numerous Old Norse sources. Most historians believe that berserkers worked themselves into a rage before battle, but some think that they might have consumed drugged foods.”
I don’t think they have anything on the berserkers of yore!
Which would have been easier had DU existed at that time
“...but some think that they might have consumed drugged foods.”
Must have been the moldy rye bread.