was forced to move many of his troops to combat this new threat. Samuel quickly regained the lost lands and advanced south. In 996, he defeated the Byzantines in the battle of Thessaloniki. During the battle, Thessaloniki's governor, Gregorios, perished and his son Ashot was captured. Elated by this success, the Bulgarians continued south. They marched through Thessaly, overcame the defensive wall at Thermopylae and entered the Peloponnese, devastating everything on their way. As a response, a Byzantine army under Nikephorus Uranos was sent after the Bulgarians, who returned north to meet it. The two armies met near the flooded river of Spercheios. The Byzantines found a place to ford, and on the night of 19 July 996 they surprised the unprepared Bulgarian army and routed it in the battle of Spercheios. Samuel's arm was wounded and he barely escaped captivity; he and his son allegedly feigned death. After nightfall they headed for Bulgaria and walked home. Research of Samuel's grave suggests that the bone in his arm healed at an angle of 140° but remained crippled. Emperor In 997, Roman died in captivity in Constantinople, ending the line of rulers started by Krum. Because of the war with Byzantium, it was dangerous to leave the throne vacant for long, and Samuel was chosen as the new Emperor of Bulgaria because he had the closest relations to the deceased emperor and was Roman's long-standing military commander. The presbyter of Duklja also marked the event: "By that time among the Bulgarian people rose one Samuel, who proclaimed himself emperor. He led a long war against the Byzantines and expelled them from the whole territory of Bulgaria, so that the Byzantines did not dare to approach it". Constantinople would not recognize the new emperor, as for the Byzantines Boris II's abdication symbolized the official end of Bulgaria and Samuel was considered a mere rebel. Instead Samuel sought recognition from the Pope, which would be a serious blow to the position of the Byzantines in the Balkans and would weaken the influence of the Patriarch of Constantinople, thereby benefiting both the See of Rome and Bulgaria. Samuel possibly received his imperial crown from Pope Gregory V. War against Serbs and Croats In 998, Samuel launched a major campaign against the Duklja to prevent an alliance between Prince Jovan Vladimir and the Byzantines. When the Bulgarian troops reached Duklja, the Serbian prince and his