The death of Uroš's father was quickly followed by the death of Preljub, who governed Thessaly. In the spring of 1356, Nikephoros Orsini landed a force on the coast of Thessaly and quickly overran it. He then followed up this success by driving despot Simeon Uroš from Aetolia and Acarnania. Simeon was paternal uncle and the closest male relative of young Emperor Uroš. Retreating to Epirus and western Macedonia, he seized Kostur and proclaimed himself Tsar in hope of becoming co-ruler, or even replacing young Uroš on the Serbian throne. His claim was not widely welcomed, and the support he gained was limited to the some southern regions. The Sabor (state council) held in Skoplje did not accept Simeon's claims and following the endorsement of the magnates, Uroš became more energetic in his political activities, publishing a number of charters. In 1358, Simeon attacked the Skadar region, trying to capture the old Serbia region of Zeta, but was defeated. Defeated in the north, Simeon again turned to south, retaking Epirus and Thessaly in 1359, where he continued to rule with the title "emperor of Serbs and Greeks".