Treaty of Berlin: The European powers redraw the map of the Balkans. Serbia, Montenegro and Romania become completely independent of the Ottoman Empire.

The Treaty of Berlin, signed on July 13, 1878, was a pivotal diplomatic agreement that reshaped the political landscape of the Balkans following the Russo-Turkish War of 1877–78. Negotiated at a congress convened by major European powers in Berlin and led by German Chancellor Otto von Bismarck, the treaty aimed to revise the earlier Treaty of San Stefano, which had heavily favored Russian interests and created a large, pro-Russian Bulgaria. This alarmed Britain and Austria-Hungary, who feared the expansion of Russian influence in Southeastern Europe. As a result, the Treaty of Berlin significantly reduced Bulgaria’s size, splitting it into three parts: the autonomous Principality of Bulgaria, the semi-autonomous Eastern Rumelia under Ottoman control, and Macedonia, which was returned to direct Ottoman rule.

The treaty also addressed the broader ethnic and political tensions in the region. Serbia, Montenegro, and Romania were recognized as fully independent states, although their territorial expansions were more limited than originally promised. Bosnia and Herzegovina were officially left under Ottoman sovereignty but were de facto occupied and administered by Austria-Hungary, a move that created long-term friction in the region. While the Treaty of Berlin was seen as a victory for the balance-of-power approach to diplomacy, it failed to resolve underlying nationalistic aspirations and ethnic rivalries in the Balkans. These unresolved tensions would later contribute to instability and were a key precursor to the outbreak of World War I.