Leidang
The institution known as leiĆ°angr (Old Norse), leidang (Norwegian), leding, (Danish), ledung (Swedish), expeditio (Latin) or sometimes lething (English), was a public levy of free farmers typical for medieval Scandinavians. It was a form of conscription to organise coastal fleets for seasonal excursions and in defence of the realm. In Anglo-Saxon England, a different system was used to achieve similar ends, and was known as the fyrd.
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