Balkan Wars
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.