Chief White Bull was a nephew to the better known Chief Sitting Bull of the Lakota People. Whereas Sitting Bull was a war lord and spiritual leader, White Bull was a warlord. He was war Chief with more battle honors then any member of his tribe, to include Crazy Horse (or so we understand, though our knowledge is spotty with Crazy Horse as he was killed so young).
But in reading White Bulls narrated autobiography he relates some amazing tales that are really interesting in the mundane reaction they had to war. The warriors would often sit around and on sudden, one, usually with battle honors, would announce he was going on a raid (to whatever neighboring tribes or settlements). Braves would join or not join as they chose and no one was slighted one way or the other. His raiding parties often consisted of only 4-8 warriors. Off they would go on adventure for glory and wealth.
This is very similar to the Vikings. Many of the viking raids were similar, very small, consisting of 30-40 men in a single long ship. Plying the waves of the North Sea seeking glory and wealth.