 Before becoming king, Harald had spent around fifteen years in exile as a mercenary and military commander in Kievan Rus' and of the Varangian Guard in the Byzantine Empire.When he was fifteen years old, in 1030, Harald fought in the Battle of Stiklestad together with his half-brother Olaf Haraldsson (later Saint Olaf).Olaf sought to reclaim the Norwegian throne, which he had lost to the Danish king Cnut the Great two years prior.