Political map of Europe & the Mediterranean 31 July 1913 (Second Balkan War): Bulgaria had gained much territory in the war against the Ottomans (First Balkan War), but less than what it had been promised. In June 1913, exactly one month after peace had been signed, it attacked Serbia for more land. However, in the war that followed (Second Balkan War), the Greeks, Montenegrins, Romanians, and Ottoman Turks sided with the Serbs, and Bulgaria ended up defeated on all sides.