Balkan Wars

The Balkan Wars were a series of wars fought in the Balkan Peninsula in 1912 (First Balkan War) and 1913 (Second Balkan War). 
The First Balkan War was fought by Greece, Serbia, Montenegro and Bulgaria (the Balkan League) against the Ottoman Empire. The main objective of the Balkan League was to annex the European territories of the Ottoman Empire, because large numbers of the people of the Balkan League lived under Ottoman rule. The war was a success and the Ottoman Empire lost almost its entire European territories.
The Second Balkan War was fought by Greece, Serbia, the Ottoman Empire and Romania against Bulgaria. Because Bulgaria felt that Greece and Serbia got more lands than they deserved, Bulgaria declared war on Greece and Serbia, which repelled the attacks. The Ottoman Empire and Romania declared war on Bulgaria, because they wanted to gain Bulgarian territories, and by the end of the Second Balkan War Bulgaria had lost almost all its gains from the First Balkan War.
The Balkan Wars resulted in huge casualties. The Bulgarians lost around 65,000 men, the Greeks 9,500, the Montenegrins, 3,000, and the Serbs at least 36,000. The Ottomans lost as many as 125,000 dead. In addition, tens of thousands of civilians died from disease and other causes.
After the Treaty of Istanbul in 1913, a population exchange was made by the Ottoman Empire with the Kingdom of Bulgaria, 9714 Muslim's (Turks and Xoraxane Roma) from Haskovo in North Thrace, was expelled to Ottoman Empire, and 9472 Orthodox Christian Bulgarian from Edirne in East Thrace was expelled to Kingdom of Bulgaria.