M. Žujović, Bogdan Popović, Jovan Skerlić, Sima Lozanić, Branislav Petronijević and several others. King Peter I gained enormous popularity following the Balkan Wars in 1912 and 1913, which, from a Serb and South Slav perspective, proved greatly successful, heralded by the spectacular military victories over the Ottomans, followed by the liberation of "Old Serbia" (Kosovo Vilayet) and Macedonia (Manastir Vilayet). The territory of Serbia doubled and her prestige among South Slavs (Croats and Slovenes in particular, and among the Serbs in Austria-Hungary, in Bosnia-Herzegovina, Vojvodina, the Military Frontier, Dalmatia, Slavonia, etc.) grew significantly, with Peter I as the main symbol of both political and cultural success. After the conflict between military and civilian representatives in the spring of 1914, King Peter chose to "retire" due to ill health, reassigning on 11/24 June 1914 his royal prerogatives to his second son heir apparent Crown Prince Alexander. World War I and its aftermath The retired King, spending most of his time in various Serbian spas, remained relatively inactive during the First World War, although occasionally, when the military situation became critical, he visited trenches on the front-line to check up on morale of his troops. His visit to the firing line prior to the Battle of Kolubara in late 1914 boosted the morale of the retreating Serbian forces and announced a counter-offensive, sparking victory against numerically superior Austro-Hungarian forces (December 1914). Another memorable visit in 1915 involved King Peter, by then 71, picking up a rifle and shooting at enemy soldiers. Following the invasion of Serbia by the joint forces of Germany, Austro-Hungary and Bulgaria in October 1915, King Peter I led the army and tens of thousands of civilian refugees through the high mountains of Albania to the Adriatic sea on a "Calvary known to few peoples". After the dramatic retreat in a harsh winter through the hostile environment of the Albanian highlands from Prizren to the Albanian littoral, a march that took more than 100,000 lives, the King and his army, exhausted by cold and famine, were eventually transported by the Allies to the Greek isle of Corfu in early 1916. For the rest of World War I King Peter I, already in very poor health, remained on Corfu, which became the seat of the Serbian government-in-exile until December 1918. On 1 December 1918 King Peter I was proclaimed King of the Serbs, Croats and Slovenes. King Peter stayed abroad