Magnus V Erlingsson (Old Norse: Magnús Erlingsson) was a King of Norway during the Civil war era in Norway.
Magnus Erlingsson was probably born in Etne in Hordaland. He was the son of Erling Skakke. His father was a Norwegian nobleman who earned his reputation crusading with Rögnvald Kali Kolsson, the Earl of Orkney. His mother was Kristin Sigurdsdatter, daughter of king Sigurd Jorsalfare who was king of Norway from 1103 to 1130. Magnus Erlingsson was named king in 1161 at the age of five. He was the first Norwegian king to be crowned. His father Erling took the title of earl and held the real power since Magnus was a minor. Erling Skakke continued to be the country’s real ruler even after Magnus had come of age.
In 1166, Sigurd Agnhatt and his foster son Olav Ugjæva raised a force in Oppland, and had Olav proclaimed king, while earl Erling Skakke was away in Denmark. Olav was the son of Maria Øysteinsdotter, the daughter of former king Øystein Magnusson. After Erling returned to Norway to fight this uprising, Olav and his men attacked Erling in an ambush at Rydjokul in Sørum. Erling was wounded and barely escaped. In 1168 Olav and his men ventured south to the Oslofjord area, but were there defeated in battle at Stanger in Våler. Sigurd was killed in the battle, but Olav escaped and went to Denmark.
Magnus' reign saw the arrival in Norway of Sverre Sigurdsson, who claimed the throne for himself. In June 1177, Sverre first led his men to Trøndelag where Sverre was proclaimed as king. Erling's position was compromised and he fell at the Battle of Kalvskinnet outside Nidaros in 1179. Several more years of warfare ended with Magnus' defeat and death in the Battle of Fimreite on June 15, 1184. Sverre attacked Magnus' fleet sending his ships into battle in squadrons, to charge and overwhelm on one ship at a time, forcing the Magnus' men to jump over to the next. As the battle proceeded, the remaining ships became extremely crammed, and then started to go down because of the weight. King Magnus is reported to have gone down on one of the last of them.