Bulgaria is a nation in southeastern Europe. After centuries of Ottoman rule, it became independent with Russian help in 18??. However, the borders of the new nation failed to encompass all of its people as Eastern Rumelia, also mostly ethnic Bulgarian, was still in Ottoman hands.
The union that Bulgaria and Eastern Rumelia sought for was declared in 1885. The Ottoman Empire forced to have the union rejected while Russia and Austria openly accepted the Bulgarian demand. The war declarations between the Ottoman Empire on the one hand and Russia and Austria-Hungary on the other hand were the beginning of the Third Global War.