Norwegian-Danish Monarch. He ruled Norway as Magnus I from 1035 to 1047 as well as Denmark from 1042 to 1047. He was born in Norway, the illegitimate son of King Olaf II (later Saint Olaf) of Norway and his English concubine Alfhild. He was born prematurely and was not expected to survive, but he grew to become a strong and healthy person. When his father was dethroned by the Danish King Cnut the Great, he went into exile to the Kievan Rus by way of Sweden, and the young Magnus accompanied him. In 1030, Olaf I returned to Norway to reclaim the throne but was killed at the Battle of Stiklestad. Magnus remained in the Kievan Rus where he was educated and trained as a warrior. When Cnut the Great died in 1035, the Norwegian noblemen did not want to be subjected to the harsh rule of his son, Svein, and his mother, Alfifa, and Magnus was brought back to Norway where he was proclaimed king at the age of 11. In 1040, he waged a campaign against Harthacnut, the king of Denmark, but a peace was arranged between them that whoever was the first to die, the other would succeed his throne. Harthacnut died in 1042 and Magnus became the king of Denmark, over the objection by Sweyn Estridsson, a nephew of Cnut the Great, who fled Denmark to England. Sweyn soon returned with an army and in 1043, Magnus' forces defeated him at the Battle of Lyrskov Heath at Hedeby, near the present-day border of Denmark and Germany, and he fled temporarily to Sweden. In 1046, Harald Sigurdsson, the half-brother of Olaf II and nephew of Magnus I returned to Norway from the east to claim the throne. Harald allied himself with Sweyn and threatened to take the throne by force. Magnus decided not to fight Harald and made him his co-king. However, Sweyn continued to put pressure on Magnus and in late 1046, Magnus drove him out of Denmark by force. Magnus died suddenly the following year in Denmark, in either the region of Zealand or in Jutland. The accounts of his death vary, from falling overboard from one of his ships and drowning, falling off a horse and succumbing to injuries received, or dying from an unknown illness. Before he died, he reportedly made Harald his heir to the Norwegian throne and Sweyn his heir to the Danish throne. His ultimate goal was to reunite all of Cnut the Great's empire by also becoming the king of England, which he did not live to attempt or achieve.