In 1038, Harald joined the Byzantines in their expedition to Sicily, in George Maniakes's (the sagas' "Gyrge") attempt to reconquer the island from the Muslim Saracens, who had established the Emirate of Sicily on the island. During the campaign, Harald fought alongside Norman mercenaries such as William Iron Arm. According to Snorri Sturluson, Harald captured four towns on Sicily. In 1041, when the Byzantine expedition to Sicily was over, a Lombard-Norman revolt erupted in southern Italy, and Harald led the Varangian Guard in multiple battles. Harald fought with the Catepan of Italy, Michael Dokeianos with initial success, but the Normans, led by their former ally William Iron Arm, defeated the Byzantines in the Battle of Olivento in March, and in the Battle of Montemaggiore in May. After the defeat, Harald and the Varangian Guard were called back to Constantinople, following Maniakes' imprisonment by the emperor and the onset of other more pressing issues. Harald and the Varangians were thereafter sent to fight in the southeastern European frontier in Bulgaria, where they arrived in late 1041. There, he fought in the army of Emperor Michael IV in the Battle of Ostrovo of the 1041 campaign against the Bulgarian uprising led by Peter Delyan, which later gained Harald the nickname the "Bulgar-burner" ("Bolgara brennir") by his skald.