now including Bulgaria, sent in 600,000 troops total. The Serbian army, fighting on two fronts and facing certain defeat, retreated into northern Albania. The Serbs suffered defeat in the Battle of Kosovo. Montenegro covered the Serbian retreat towards the Adriatic coast in the Battle of Mojkovac in 6–7 January 1916, but ultimately the Austrians also conquered Montenegro. The surviving Serbian soldiers were evacuated by ship to Greece. After conquest, Serbia was divided between Austro-Hungary and Bulgaria. In late 1915, a Franco-British force landed at Salonica in Greece to offer assistance and to pressure its government to declare war against the Central Powers. However, the pro-German King Constantine I dismissed the pro-Allied government of Eleftherios Venizelos before the Allied expeditionary force arrived. The friction between the King of Greece and the Allies continued to accumulate with the National Schism, which effectively divided Greece between regions still loyal to the king and the new provisional government of Venizelos in Salonica. After intense negotiations and an armed confrontation in Athens between Allied and royalist forces (an incident known as Noemvriana), the King of Greece resigned and his second son Alexander took his place; Greece officially joined the war on the side of the Allies in June 1917. The Macedonian front was initially mostly static. French and Serbian forces retook limited areas of Macedonia by recapturing Bitola on 19 November 1916 following the costly Monastir offensive, which brought stabilisation of the front. Serbian and French troops finally made a breakthrough in September 1918 in the Vardar offensive, after most of the German and Austro-Hungarian troops had been withdrawn. The Bulgarians were defeated at the Battle of Dobro Pole, and by 25 September British and French troops had crossed the border into Bulgaria proper as the Bulgarian army collapsed. Bulgaria capitulated four days later, on 29 September 1918. The German high command responded by despatching troops to hold the line, but these forces were far too weak to re-establish a front. The disappearance of the Macedonian front meant that the road to Budapest and Vienna was now opened to Allied forces. Hindenburg and Ludendorff concluded that the strategic and operational balance had now shifted decidedly against the Central Powers and, a day after the Bulgarian collapse, insisted on an immediate peace settlement. Ottoman Empire The Ottomans threatened Russia's Caucasian territories and Britain's communications with India via the Suez Canal. As the conflict progressed, the Ottoman