1912-1913. In November 1918, shortly before the founding of the Kingdom of Serbs, Croats and Slovenes in December 1918, Serbia acquired some new territories like Srem, Banat, Bačka and Montenegro and which later became part of the new kingdom. The most prominent prime minister during the reign of Peter I was Nikola Pašić. At the beginning of Peter's reign Pašić opposed the new king, calling his accession to the throne unlawful. However, he quickly changed his mind after seeing that the Serbian people accepted King Peter. As it turned out, the only conflict he had with Peter during the 18-year reign concerned the king's salary. Peter I of Serbia saw Imperial Russia as Serbia's main ally. Russia opposed the previous politics of the Obrenović dynasty which heavily relied on Austria-Hungary, which the Serbian public detested. First Balkan War The First Balkan War began in October 1912 and ended in May 1913. It involved military actions of the Balkan League (Bulgaria, Serbia, Greece and Montenegro) against the Ottoman Empire. The combined armies of the Balkan states overcame the numerically inferior and strategically disadvantaged Ottoman armies and achieved rapid success. As a result of the war, the allies captured and partitioned almost all remaining European territories of the Ottoman Empire. In May 1912 the Albanian Hamidian revolutionaries, who wanted to re-install Sultan Abdul Hamit II to power, drove the Young Turkish forces out of Skopje and pressed south towards Manastir (present day Bitola), forcing the Young Turks to grant effective autonomy over large regions in June 1912. Serbia, which had helped arm the Albanian Catholic and Hamidian rebels and had sent secret agents to some of the prominent leaders, took the revolt as a pretext for war. Serbia, Montenegro, Greece, and Bulgaria had all been in talks about possible offensives against the Ottoman Empire before the Albanian revolt of 1912 broke out; a formal agreement between Serbia and Montenegro had been signed on 7 March. On 18 October 1912, Peter I of Serbia issued a declaration, "To the Serbian People", which appeared to support Albanians as well as Serbs: "The Turkish governments showed no interest in their duties towards their citizens and turned a deaf ear to all complaints and suggestions. Things got so far out of hand that no one was satisfied with the situation in Turkey in Europe. It became unbearable for the Serbs, the Greeks and for the Albanians,