final Treaty of Peace, Friendship and Mutual Protection was signed at Thessaloniki on 1 June 1913, by the Greek ambassador to Belgrade, Ioannis Alexandropoulos, and the Serbian ambassador to Athens, Mateja Bošković. Article 1 gave a mutual guarantee of the signatories' territorial possessions, concluded a defensive alliance and precluded each government from unilaterally concluding a peace treaty. Article 2 pledged the two states to a common front in the negotiating table against Bulgaria. Article 3 delineated the Greek–Serbian border (presently the border of Greece and the Republic of North Macedonia) based on the demarcation line between the respective armies. Articles 4 and 5 stated each country's territorial claims on Bulgarian-controlled territory (the line Gevgelija–Vardar River–Bregalnica–Osogovska Planina for the Serbs and Belasica–Eleftheres Gulf for the Greeks), committed them to seek international mediation, and to meet Bulgarian armed aggression towards either signatory with all available forces. The attendant military convention obliged each country to come to the other's aid with all available forces should either be attacked by a third power, or, if one of the signatories declared war first, to maintain a favourable neutrality and conduct a partial mobilization (40,000 men for Greece and 50,000 for Serbia). The signature of the Greek–Serbian alliance marked the demise of the Balkan League. On 30 June, Bulgarian troops attacked the Greek and Serbian lines, beginning the Second Balkan War. Impact and aftermath The alliance played an important role in World War I, when Serbia was attacked by Austria. Venizelos mobilized the Greek army, but met with the refusal of the Germanophile King Constantine I to enter the war on the side of the Entente Powers. In an attempt to force the king's hand, in mid-1915 Venizelos allowed a British-French force to land in Thessaloniki in order to aid the Serbs, establishing the Salonica front. The crisis between Prime Minister and King over the issue of the country's participation in the war led to the National Schism, which plagued Greek political life until the 1930s. The Treaty of Alliance was finally unilaterally cancelled by the new Kingdom of the Serbs, Croats and Slovenes in 1924, as a reaction to the controversial Greek-Bulgarian Politis–Kalfov Protocol on minorities. See also Balkan League, 1912 Greek–Serbian Alliance of 1867 References Sources Treaties concluded in 1913 Second Balkan War Greece–Serbia military relations Serbia 1913 Greece 1913 Military alliances involving Greece Military alliances involving Serbia History of Greece (1909–1924) Kingdom of