In 1353 the Pope, Innocent VI, persuaded King Louis of Hungary to undertake a crusade against Serbia in the name of Catholicism, but Stephen defeated him and re-established his frontier along the Save and Danube. Later he conquered the southern half of Dalmatia, and extended his empire as far north as the river Cetina. In 1354 Stephen Dušan himself approached the Pope, offering to acknowledge his spiritual supremacy, if he would support him against the Hungarians and the Turks. The Pope sent him an embassy, but eventually Stephen could not agree to the papal conditions, and concluded an alliance, of greater practical utility, with the Venetians. In 1355, however, he suddenly died, at the age of forty-six, and thus the further development and aggrandisement of his country was prematurely arrested. Stephen Dušan made a great impression on his contemporaries, both by his imposing personal appearance and by his undoubted wisdom and ability. He was especially a great legislator, and his remarkable code of laws, compiled in 1349 and enlarged in 1354, is, outside his own country, his greatest title to fame. During Stephen Dušan’s reign the political centre of Serbia, which had for many years gradually tended to shift southwards towards Macedonia, was at Skoplje (Üsküb in Turkish), which he made his capital. Stephen Dušan’s empire extended from the Adriatic in the west to the river Maritsa in the east, from the Save and Danube in the north to the Aegean; it included all the modern kingdoms of Serbia, Montenegro, Albania, and most of Greece, Dalmatia as far north as the river Cetina, as well as the fertile Morava valley, with Nish and Belgrade—the whole eastern part of Serbia, which had for long been under either Bulgar or Magyar control. It did not include the cities of Salonika or Ragusa, nor any considerable part of the modern kingdom of Bulgaria, nor Bosnia, Croatia, North Dalmatia, nor Slavonia (between the Save and Drave), ethnologically all purely Serb lands. From the point of view of nationality, therefore, its boundaries were far from ideal.