The institution known as leiðangr (Old Norse), leidang (Norwegian), leding (Danish), ledung (Swedish), expeditio (Latin) or sometimes lething (English), was a form of conscription (mass levy) to organize coastal fleets for seasonal excursions and in defense of the realm typical for medieval Scandinavians and, later, a public levy of free farmers. In Anglo-Saxon England, a different system was used to achieve similar ends, and was known as the fyrd. The first recorded instance of a Norse lething is disputed among scholars. There is considerable evidence that substantiates its existence in the late 12th century. However, there are also written sources and archeological evidence which indicate that the lething system was introduced as early as the tenth century, if not earlier. The age of the lething is disputed among scholars. The Icelandic sagas link the introduction of the lething to King Haakon I (The Good) of Norway in the tenth century. The first known lethings are found during the ninth and tenth centuries when Sea Kings could be elected. These rulers were given provisional authority over men who had to assemble for an allotted time to achieve certain limited and pre-agreed goals. The temporary kingships of early Viking society had no power of enforcement over their men as they exercised authority only by consent. The leidangr of Norway is first mentioned in 985 AD by the Skaldic courtly poets of Jarl Haakon of Western Norway and his son Erik. In each poem, the princes are praised for summoning the ships of the leidangr to the Battle of Hjörungavágr against a Danish fleet. The King of Norway, Harald Hardrada, is later praised by two court Skalds for summoning the leidangr to attack Denmark. Harald is also called king of the leidangr and the latter is termed almenningr, the duty and right of all men. During the 11th century Danish naval forces, though not termed leidangr, are sporadically praised as led by Danish kings (as Knut in his conquest of England).