Serbia defeated the Bulgarian Empire in the Battle of Velbazhd in 1330, becoming a military superpower during the middle part of the 14th century under the dynamic Stephen Uroš IV Dušan (1331–55), who created the Serbian Empire. It included Macedonia, Albania, Epirus and Thessaly, reaching from the Drina and Danube rivers as far south and east as the Gulf of Patras and the Rhodope Mountains by 1350. A large part of this expansion was at the expense of the Byzantine Empire. Dušan set his sights on the Byzantine capital of Constantinople itself, dividing his lands into 'Serbia' and 'Romania'. Dušan was crowned Emperor (Tsar) of Serbs and Romans in 1345. He modeled his court on that of Constantinople, calling his officials by Byzantine titles such as caesar, despot, sebastokrator and logotet (logothete). However, following his death, the Serbian Empire gradually disintegrated under his successor Stephen Uroš V (1355–71). One Byzantine chronicler noted with evident satisfaction that the Serbian nobility were soon divided into '10,000 factions', while John VI Kantakouzenos wrote that Dušan's empire fell 'into a thousand pieces'.