A hersir was a local Viking military commander of a hundred (a county subdivision) of about 20 men and owed allegiance to a jarl or king. They were also aspiring landowners, and, like the middle class in many feudal societies, supported the kings in their centralization of power.
The hersir was often equipped with a conical helmet and a short mail coat. Most would wield a pattern-welded steel sword, mostly augmented with a wooden shield. They were also known to wield one- or even two-handed axes.
 Military tactics
The hersir would always fight on foot, usually as part of a shield wall formation. Another formation was also used, the Svinfylking, which was a variation to the shield wall but with several wedge-like formations pointing towards the enemy creating a zig zag pattern. Although excellent against other foot troops the Vikings were frequently defeated by mounted troops.
 Later developments
By the end of the 10th century, the independence of the hersir was gone, and he was now a regional servant of the Norwegian king.
 Hersirs in history
Hersir was the name of a man in Rígsþula whose daughter Erna married Jarl, the first earl.
A Swedish hersir, Jarlabanke Sigfastsson, has become notable for the about 20 Jarlabanke Runestones that he raised together with his relatives.
Ketill Flatnose was a Norwegian hersir of the 9th century.