Magnusson was the oldest son of Magnus Lagabøte
(Magnus Lawmender) and took over as king when his father died in 1280.
When Eirik was a small boy, he suffered head injuries in a riding accident,
which has often been taken as the reason for his being so inept at ruling
the country. His handicap was exploited by individuals greedy for power.
Among those who served as his guardians were his mother, the Danish princess
Ingeborg, and the baron, Audun Hugleiksson. As a result, Eirik's was a
more severe reign than that of Magnus Lagabøte.
Among many changes in domestic politics was the loss by the church of many of its privileges. The conflict led to a strengthened power base for the secular magnates and the archbishop, Jon Raude, was forced to flee the country. The conflict persisted until the archbishop died in 1282. As a result, Eirik was given the sobriquet «priest hater», a completely unjustified epithet. He was never, in fact, involved in this conflict with the church and as an adult he was well disposed towards the clergy and was on good terms with the pope.
The foreign policy of the regency led to war with Denmark
and with the Hanseatic cities. The quarrel with the Hanseatic League was
originally concerned with the privileges of the German tradesmen in Norwegian
cities. When some of the German merchant ships were seized, the Hanseatic
cities and Denmark joined forces in a trade blockade preventing Norway
from importing grain. In the end the Norwegians had to yield and were forced
not only to pay compensation for damages but also to grant the German merchants
greater privileges. This caused a financial crisis unprecedented in Norwegian
history. The conflict with Denmark lasted through Eirik’s reign. Duke
Håkon, who was Eirik’s younger brother, took over as king when
Eirik died in 1299.