Harald Finehair, a king in Upplönd, imposed his rule over Norway after defeating a coalition of jarls at the naval battle of Hafsfjord c. 875. Although his line ended in 970, another sea king, Olaf Tryggvasson, used his Viking fleet, and Christian institutions, to become king of Norway. Olaf fell fighting a Danish rival, Swein Forkbeard, at the naval battle of Svöld, and Norwegians again acknowledged a Danish king.