 Holy Roman Emperor Otto II assembled a great army of Saxons, Franks, Frisians, and Wends to fight the Norse pagan Danes.Olaf was part of this army because his father-in-law was king of Wendland.Otto's army met the armies of King Harald Bluetooth and Haakon Jarl, the ruler of Norway under the Danish king, at Danevirke, a great wall near Schleswig.