Complex sentence: Czar Dušan dispatched Đuraš Ilijić to relieve the siege, who left with an Army and his two brothers Nikola and Vladin as well as his sons and nephews.
Split into simpler sentences: Czar Dušan dispatched Đuraš Ilijić to relieve the siège. He left with an army and his two brothers Nikola and Vladin as well as his sons and nephews.