Magnus V of Norway

Magnus Erlingsson was born in 1156, during Norway's long civil war era when rival claimants fought over the throne. He became Magnus V and worked to cement primogeniture — the principle that the crown passes to the eldest son — as the rule for Norwegian succession. The reform aimed to end the chaos of competing royal lines. On 15 June 1184, his fleet met Sverre Sigurdsson's forces at the Battle of Fimreite. Magnus was killed in the fighting, and Sverre took the crown.