Bulgaria joined the Ottoman Empire in 1396. In April 1876, there were many uprisings against Ottoman control in Bulgaria. The Ottomans' suppression of the revolts drew gave opportunity for international involvement, and in April 1877, Russia declared war on the Ottoman Empire.
The San Stefano peace deal, signed in March 1878, brought an end to the conflict. The other great nations of the period believed that the peace accord established a Bulgaria that was too large and had too much power in the area. As a result, in 1878, the Treaty of Berlin split Southern Bulgaria (Eastern Rumelia) from the Principality of Bulgaria and restored it to the Ottoman Empire with partial autonomy.
Bulgarians believed the Berlin Treaty judgement was unjust. Over the next seven years, originally peaceful rallies turned into insurrection and violence. In February 1885, the Bulgarian Secret Central Revolutionary Committee was created, and it staged events and revolts in Eastern Rumelia towns to aid in the unification drive. On September 6, 1885, Bulgaria and Eastern Rumelia announced their unity in Plovdiv.
The unity infuriated numerous major nations, resulting in the Serbo-Bulgarian War. Bulgaria was victorious from the struggle and achieved acceptance of its boundaries.
