Håkon IV of Norway, also known as Håkon Håkonsson, was born in 1204 and became king in 1217. He is best known for his efforts to strengthen the monarchy and unify Norway during a time of internal conflict. His reign lasted until 1263, making him one of the longest-serving kings in Norwegian history. Håkon IV was a key figure in the Norwegian civil wars, which were a series of conflicts over the throne. He also played a significant role in the Kalmar Union, which sought to unite the crowns of Denmark, Norway, and Sweden. His leadership helped establish a more centralized government in Norway.