along the Adriatic Sea awarded to it in 1915. Romanian participation Despite secretly agreeing to support the Triple Alliance in 1883, Romania increasingly found itself at odds with the Central Powers over their support for Bulgaria in the 1912 to 1913 Balkan Wars and the status of ethnic Romanian communities in Hungarian-controlled Transylvania, which comprised an estimated 2.8 million of the 5.0 million population. With the ruling elite split into pro-German and pro-Entente factions, Romania remained neutral in 1914, arguing like Italy that because Austria-Hungary had declared war on Serbia, it was under no obligation to join them. They maintained this position for the next two years, while allowing Germany and Austria to transport military supplies and advisors across Romanian territory. In September 1914, Russia had acknowledged Romanian rights to Austro-Hungarian territories including Transylvania and Banat, whose acquisition had widespread popular support, and Russian success against Austria led Romania to join the Entente in the August 1916 Treaty of Bucharest. Under the strategic plan known as Hypothesis Z, the Romanian army planned an offensive into Transylvania, while defending Southern Dobruja and Giurgiu against a possible Bulgarian counterattack. On 27 August 1916, they attacked Transylvania and occupied substantial parts of the province before being driven back by the recently formed German 9th Army, led by former Chief of Staff Falkenhayn. A combined German-Bulgarian-Turkish offensive captured Dobruja and Giurgiu, although the bulk of the Romanian army managed to escape encirclement and retreated to Bucharest, which surrendered to the Central Powers on 6 December 1916. Approximately 16% of the pre-war Austro-Hungarian population consisted of ethnic Romanians, whose loyalty faded as the war progressed; by 1917, they made up more than 50% of the 300,000 deserters from the Imperial army. Prisoners of war held by the Russian Empire formed the Romanian Volunteer Corps who were repatriated to Romania in 1917. Many fought in the battles of Mărăști, Mărășești and Oituz, where with Russian support the Romanian army managed to defeat an offensive by the Central Powers and even take back some territory. Left isolated after the October Revolution forced Russia out of the war, Romania signed an armistice on 9 December 1917. Shortly afterwards, fighting broke out in the adjacent Russian territory of Bessarabia between Bolsheviks and Romanian nationalists, who requested military assistance from their compatriots. Following their intervention, the independent Moldavian Democratic Republic was formed in February 1918, which voted for union with