Raised by conscription, the Bulgarian Army comprised some 85,000 troops in peacetime. All men aged between 20 and 46 could be called up during a war. After the Balkan Wars (1912-13) the size of the army was increased to ten divisions. Each division of 24,000 men were supported by cavalry squadrons, machine-gun troops and field artillery.

With no major arms industry, the Bulgarian Army relied heavily on supplies of shells, bullets, artillery and machine guns from the German Army. The German Army Air Service also provided both personnel and aircraft.

Bulgarian troops were concentrated on the Balkan Front and took part in the invasion of Serbia in October 1915. They also kept guard over Allied troops in Salonika and protected the Thrace border against attack from Greece.

The Bulgarian Army retreated during the Vardar Offensive and this continued until the Armistice was signed on 30th September, 1918.

About 1.2 million Bulgarians fought during the First World War. An estimated 100,000 were killed and some 160,000 wounded. After the war the Neuilly Treaty restricted the Bulgarian Army to 33,000 men.