By 1015, Bulgaria had been embroiled in almost thirty years of war with the Byzantine Empire, and Gavril Radomir had succeeded Samuel, who died on 6 October 1014 after the disastrous Battle of Kleidion. However, from the outset Radomir's position was insecure: Ivan Vladislav, as a son of the elder of the Cometopouli brothers, could lay claim on the throne based on seniority. During that time the Byzantine Emperor Basil II campaigned deep into Bulgarian territory. He retook the previously lost town of Voden (Edessa) and laid siege to the massive fortress of Maglen, situated to the north-west. Gavril Radomir did not have enough forces and was unable to interfere and could only watch the course of the events from the nearby Lake Ostrovo. His inability to cope with the Byzantine threat aroused discontent among the nobility and Ivan Vladislav became their chosen leader. The fall of Maglen sealed Gavril Radomir's fate—in the late summer of 1015, while hunting near Ostrovo (Arnissa), he was murdered by his cousin, perhaps at the behest of Byzantine agents. Ivan Vladislav then seized the Bulgarian throne and took steps to ensure his position against potential rivals.