When he was fifteen years old, in 1030, Harald fought with his half-brother Olaf against Cnut (Canute). Olaf sought to reclaim the Norwegian throne, which he had lost to the Danish king Cnut the Great two years before. In the battle, Olaf and Harald were defeated by forces loyal to Cnut. Harald was forced into exile to Kievan Rus' (early form of Russia). After some time in the army of Grand Prince Yaroslav the Wise, he moved on to Constantinople with his companions around 1034. In Constantinople, he commanded the Byzantine Varangian Guard. 