Answer:
Serbia
Step-by-step explanation:
Serbia during World War I had a prominent role, mainly in the unleashing and in the conclusion of the contest. The initial Austro-Serbian crisis of the summer of 1914 was transformed into a war that spanned the entire continent as a result of alliances between European countries. Despite winning the Austro-Hungarian Army in the first fights, the Serbs then had to leave their country and withdraw through Albania, harassed by the Austro-German divisions that invaded from the north and west, and the Bulgarians who did so from the East. Protected by the Allies, they continued the fight against the central Empires, unlike their attached straits, the Montenegrins. The remnants of the Serbian Army, refurbished, were sent to the Macedonian front, where they managed to recover some territories of southern Serbian Macedonia; The rest of the country, however, was occupied by the Austrohúgnaros or annexed to Bulgaria. After two more years of a war of attrition, the Army of the East, composed largely of Serbian units, broke the enemy lines and freed the kingdom in a few weeks in the fall of 1918. Political representatives of the southern Slavs of the Austro-Hungarian Empire, at that time in disintegration, they proclaimed independence and shortly after, on December 1, they joined the kingdoms of Serbia and Montenegro to form the new Kingdom of the Serbs, Croats and Slovenes.