 Complete the following phrase:  Dušan had grand intentions to hold Belgrade, Mačva and Hum, conquer Durrës, Phillipopolis, Adrianople, Thessalonica, and Constantinople, and to place himself at the head of a grand crusading army to drive the Muslim Turks from Europe. His premature death created a large power vacuum in the Balkans, that ultimately enabled Turkish invasion and Turkish rule 