The growing power of the Serbian Kingdom from the late 13th century raised serious concerns in the traditional Balkan powers Bulgaria and Byzantium which agreed for joint military actions against Serbia in 1327. Three years later the bulk of the Bulgarian and Serbian armies clashed at Velbazhd and the Bulgarians were caught by surprise. Serbian victory shaped the balance of power in Balkans in the next two decades. The Bulgarians did not lose territory after the battle but were unable to stop the Serbian advance towards Macedonia. Serbia managed to conquer Macedonia and parts of Thessaly and Epirus reaching its greatest territorial extent ever. Their new King Stefan Dušan was crowned Emperor with Bulgarian help in 1346.