The Bagler War was a conflict in Norway during the early 13th century, primarily between two factions: the Baglers and the Birkebeiners. The Baglers supported the claim of the church and the king's authority, while the Birkebeiners were loyal to the rightful king, Haakon IV. The war lasted from 1240 to 1247 and was marked by several battles and shifting alliances. The conflict arose from political and territorial disputes following the death of King Inge II. The Bagler War significantly impacted Norway's political landscape, leading to the eventual consolidation of power under Haakon IV, who became a key figure in unifying the country.