Once the Bulgarian advance into Romania and Greece halted, conditions at the front deteriorated rapidly and political support for the war eroded. By 1916 poor allocation of supplies created shortages for both civilians and soldiers, and a series of government reorganizations provided no relief. By 1917 the military stalemate and poor living conditions combined with news of revolution in Russia to stir large-scale unrest in Bulgarian society. The agrarians and socialist workers intensified their antiwar campaigns, and soldiers' committees formed in army units. Bolshevik antiwar propaganda was widely distributed in Bulgaria, and Russian and Bulgarian soldiers began fraternizing along the Moldavian front. In December 1917, Dimitur Blagoev, founder and head of the Social Democratic Party, led a meeting of 10,000 in Sofia, demanding an end to the war and overthrow of the Bulgarian government. A wave of unrest and riots, including a "women's revolt" against food and clothing shortages, swept through the country in 1918.

The government position weakened further when the Treaty of Bucharest, which divided the territory of defeated Romania among the central powers, left part of the disputed Romanian territory of Dobruja outside Bulgarian control. Having failed to secure even the least important territory promised by its war policy, the Radoslavov government resigned in June 1918. The new prime minister, Aleksandur Malinov, tried to unite the country by appointing the agrarian Aleksandur Stamboliiski to his cabinet. But Malinov had vowed to fight, and the BANU leader refused the post as long as Bulgaria remained in the war. By September the Bulgarian army was thoroughly demoralized by antiwar propaganda and harsh conditions. A battle with the British and French at Dobro Pole brought total retreat, and in ten days Entente forces entered Bulgaria. On September 29, the Bulgarians signed an armistice and left the war.

Data as of June 1992