A
fyrd was a type of early
Anglo-Saxon army that was mobilized from freemen to defend their
shire, or from select representatives to join a
royal expedition. Service in the fyrd was usually of short duration and participants were expected to provide their own arms and provisions. The composition of the fyrd evolved over the years, particularly as a reaction to raids and invasions by the
Vikings. The system of defence and conscription was reorganised during the reign of
Alfred the Great, who set up 33 fortified towns (or
burhs) in his
kingdom of Wessex. The amount of taxation required to maintain each town was laid down in a document known as the
Burghal Hidage. Each lord had his individual holding of land assessed in hides. Based on his land holding, he had to contribute men and arms to maintain and defend the burhs. Non-compliance with this requirement could lead to severe penalties.