Magnus III Olafsson (Old Norse: Magnús Óláfsson, Norwegian: Magnus Olavsson; 1073 – 24 August 1103), better known as Magnus Barefoot (Old Norse: Magnús berfœttr, Norwegian: Magnus Berrføtt), was the King of Norway from 1093 until his death in 1103. His reign was marked by aggressive military campaigns and conquest, particularly in the Norse-dominated parts of Ireland and Britain, where he extended his rule to the Kingdom of the Isles and Dublin.
As the only son of King Olaf Kyrre, Magnus was proclaimed king in southeastern Norway shortly after his father's death in 1093. In the north his claim was contested by his cousin, Haakon Magnusson (son of King Magnus Haraldsson), and the two co-ruled uneasily until Haakon's death in 1095. Disgruntled members of the nobility refused to recognise Magnus after his cousin's death, but the insurrection was short-lived. After securing his position domestically, Magnus campaigned around the Irish Sea from 1098 to 1099. He raided through Orkney, the Hebrides and Mann (the Northern and Southern Isles), and ensured Norwegian control by a treaty with the Scottish king. Based on Mann during his time in the west, Magnus had a number of forts and houses built on the island and probably also obtained suzerainty of Galloway. He sailed to Wales later in his expedition, gaining the support of Anglesey (and the Gwynedd) after aiding against the invading Norman forces from the island.
