On one bank of a river, dismayed French, Russian, Italian, and British soldiers watch Bulgaria drift from its broken Russian leash to the opposite bank where German, Austrian and Turkish soldiers express satisfaction and delight. The river leads, in the distance, to Istanbul. Still held by British tethers (and moneybag) are Greece and Romania.

ЧЕТВОРНИЯ СЪЮЗЪ

Quadruple Alliance

E. A. Schwerdtfeger & Co. A.G. Berlin N. 85

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With no prior declaration of war, Bulgaria joined Germany and Austria-Hungary in their invasion of Serbia on October 14, 1915, becoming the fourth and final Central Power.

Victorious in the First Balkan War of 1912–13, Bulgaria was dissatisfied with the terms of the treaty ending it and attacked its former allies Serbia and Greece. It was defeated when Romania struck its rear.

Bulgaria signed a secret treaty with Germany and Austria-Hungary on July 17, 1915, and concluded a military convention with Germany September 6. The country began mobilizing on September 23.

As German-Austro-Hungarian troops advanced into Serbia's northwest, Bulgaria invaded its neighbor from the east. The Bulgarians also struck Allied forces trying to aid Serbia from Salonica to the south. Isolated and unsupported, Serbia fell.

In May 1916, a German-Bulgarian force advanced on Fort Rupel in northeast Greece. The garrison resisted, but was ordered by the Government to surrender. The incident exacerbated the animosity between the Greek Government and the Allies.

When Romania entered the war in 1916, Bulgarian troops helped defeat the new Entente ally, particularly in Dobruja.

The Allies took Monastir, Serbia in late 1916, but in 1917, Bulgarians held the Salonica front against the Allied army.

Germany's 1918 offensives on the Western front left few resources elsewhere, but on September 14 the Allies attacked, advancing through the mountains against the Bulgarian right. Hoping for an orderly retreat, the Bulgarian left withdrew, but into narrow mountain passages where British aircraft strafed and bombed, turning the retreat into a rout.

Facing civil unrest and soviets being formed in some cities, Bulgaria signed an Armistice on September 29.

Bulgaria is a country in Europe.

More about Bulgaria:

Statistics for Bulgaria (1)

Type	Statistic
Population	4,467,000

Some places in Bulgaria (1)

Click to View	Location Type
Sofia	City

Some people from Bulgaria (1)

Last Name	First Name	Full Name	Role
Ferdinand of Bulgaria		Ferdinand of Bulgaria

Some books about Bulgaria (2)

Title	Author Last Name	Author First Name
The Gardeners of Salonika	Palmer	Alan
The Balkans, A Laboratory of History	Sloane	William