Stefan Dušan was the most powerful Serbian ruler in the Middle Ages and remains a folk hero to Serbs. Dušan, a contemporary of England's Edward III, is regarded with the same reverence as the Bulgarians feel for Tsar Simeon, the Poles for Sigismund I the Old, and the Czechs for Charles IV. According to Steven Runciman, he was "perhaps the most powerful ruler in Europe" during the 14th century. His state was a rival to the regional powers of Byzantium and Hungary, and it encompassed a large territory, which would also be his empire's greatest weakness. By nature a soldier and a conqueror, Dušan also proved to be very able but nonetheless feared ruler. His empire however, slowly crumbled at the hands of his son, as regional aristocrats distanced from the central rule.