The Austrian treatment of the Slavs was a source of constant irritation to Serbia. Roumania had a divided feeling. Her loss of Bessarabia to Russia had caused ill feeling, but in Austria's province of Transylvania there were millions of Roumanians, whom Roumania desired to bring under her rule. Greece was fearful of Russia, because of Russia's desire for the control of Constantinople. All of these nations, too, were deeply conscious of the Austro-German ambitions for extension of their power through to the East. Each of these principalities was also jealous of the other. Bulgaria and Serbia had been at war; many Bulgarians were in the Roumanian territory, many Serbians, Bulgarians and Greeks in Macedonia. There was only one tie in common, that was their hatred of Turkey. In 1912 a league was formed, under the direction of the Greek statesman, Venizelos, having for its object an attack on Turkey. By secret treaties arrangements were made for the division of the land, which they hoped to obtain from Turkey.
War was declared, and Turkey was decisively defeated, and then the trouble began. Serbia and Bulgaria had been particularly anxious for an outlet to the sea, and in the treaty between them it had been arranged that Serbia should have an outlet on the Adriatic, while Bulgaria was to obtain an outlet on the Ægean. The Triple Alliance positively refused Serbia its share of the Adriatic coast. Serbia insisted, therefore, on a revision of the treaty, which would enable her to have a seaport on the Ægean.
An attempt was made to settle the question by arbitration, but King Ferdinand refused, whereupon, in July, 1913, the Second Balkan War began. Bulgaria was attacked by Greece and Serbia, and Turkey took a chance and regained Adrianople, and even Roumania, which had been neutral in the First Baltic War, mobilized her armies and marched toward Sofia. Bulgaria surrendered, and on the 10th of August the Treaty of Bucharest was signed by the Balkan States.
As a result of this Bulgaria was left in a thoroughly dissatisfied state of mind. She had been the leader in the war against Turkey, she had suffered heavy losses, and she had gained almost nothing. Moreover she had lost to Roumania, a territory containing a quarter of a million Bulgarians, and a splendid harbor on the Black Sea. Serbia and Greece were the big winners. Such a treaty could not be a final settlement. The Balkans were left seething with unrest. Serbia, though she had gained much, was still dissatisfied. Her ambitions, however, now turned in the direction of the Jugoslavs under the rule of Austria, and it was her agitation in this matter which directly brought on the Great War. But Bulgaria was sullen and ready for revenge. When the Great War began, therefore, Roumania, Serbia, Montenegro and Greece were strongly in sympathy with Russia, who had been their backer and friend. Bulgaria, in spite of all she owed to Russia in the early days, was now ready to find protection from an alliance with the Central Powers. Her feeling was well known to the Allies, and every effort was made to obtain her friendship and, if possible, her aid.