In the early 1900s Bulgaria got involved in a number of wars, including wars with Serbia, the Balkan Wars, and World War I (WWI). In 1912 and 1913 the Balkan Wars broke out to finally end Ottoman Turkish domination over the Balkan Peninsula. The first of these wars united Serbia, Montenegro, Bulgaria, and Greece against the Turks, which ended with a Turkish defeat. War however broke out the following year with the new Turkish government, and again the Balkan countries won this war to finally end Turkish dominance in the region. Then, during WWI, Bulgaria joined Austria-Hungary to fight neighboring Serbia, but soon found itself on the losing side of the battle as Bulgaria lost both territory and a great amount of its population to both deaths and border shifts.
During World War II (WWII) Bulgaria joined the Axis powers, but in the course of the war, their tsar died and the country was thrown into domestic chaos, while trying to still manage the war. A communist group rose to power and switched allegiances, joining the Soviets and the Allies.
After WWII Bulgaria remained closely tied to the Soviet Union as a communist country. Like much of communist Europe, communism collapsed in Bulgaria in 1990, but the country has struggled to gain traction on any consistently positive economic growth, although it has grown in spurts. More recently Bulgaria joined both NATO and the European Union (EU).