Russia imposed the Treaty of San Stefano on the Ottoman Empire to end the Russo-Turkish War (1877–78). It proposed a large Bulgarian principality and recognized the independence of Serbia, Montenegro, and Romania, raising alarm among other European powers about Russia’s influence. This set the stage for an international renegotiation in Berlin.
In a separate agreement connected to the wider diplomatic crisis, the United Kingdom and the Ottoman Empire concluded the Cyprus Convention. Britain received administrative control of Cyprus in exchange for supporting the Ottomans at the upcoming Congress of Berlin. The move strengthened Britain’s position in the eastern Mediterranean while the Balkan settlement was being negotiated.
The major European powers met in Berlin to replace the Treaty of San Stefano with a new settlement. The congress aimed to limit Russian gains and reduce the risk of renewed war among the great powers. Its decisions would reshape borders and political status across the Balkans.
Albanian leaders created the League of Prizren in reaction to plans to transfer Albanian-inhabited districts to neighboring states. The league tried to influence the Congress of Berlin and later organized armed resistance to some border changes. Its activity helped turn local defense efforts into a more recognizable Albanian nationalist movement.
The Treaty of Berlin replaced the San Stefano settlement and became the new international framework for the region. It recognized the independence of Serbia, Montenegro, and Romania, and restructured the Bulgarian settlement into a smaller Principality of Bulgaria plus the autonomous province of Eastern Rumelia under Ottoman sovereignty. The treaty also authorized Austria-Hungary to occupy and administer Bosnia and Herzegovina, tying Balkan outcomes to great-power rivalry.
Acting under the Treaty of Berlin, Austria-Hungary launched a military occupation of Bosnia and Herzegovina. The occupation met armed resistance and required a major campaign to establish control. This marked a major shift: Ottoman authority remained in name, but day-to-day power moved to Vienna.
Bulgarian activists and local supporters launched an uprising in Ottoman Macedonia, partly driven by opposition to the Treaty of Berlin’s borders. Fighting continued for months and ended in defeat, with many refugees fleeing into the Principality of Bulgaria. The revolt showed how the treaty’s map did not match local expectations and helped keep the “Macedonian Question” politically active.
By late 1878, Austria-Hungary had suppressed most organized resistance and completed its initial military campaign. Bosnia and Herzegovina remained formally Ottoman, but Austria-Hungary now administered the provinces in practice. This new arrangement became a long-term source of tension in the region.
After extended negotiations influenced by the Berlin framework, Greece and the Ottoman Empire finalized a new border settlement. The Convention of Constantinople resulted in the cession of most of Thessaly and the Arta area to Greece. It showed that the 1878 settlement continued to be adjusted through diplomacy rather than a single final decision.
A political coup in Plovdiv led Eastern Rumelia—an autonomous Ottoman province created by the Treaty of Berlin—to proclaim union with the Principality of Bulgaria. The move challenged the Berlin system without immediately overthrowing Ottoman sovereignty in law. It shifted the focus from diplomatic borders to facts created on the ground.
Serbia’s attempt to challenge the Bulgarian-Eastern Rumelian union led to war, but the final peace restored the prewar border. The Treaty of Bucharest ended the conflict while leaving the union intact in practice. This outcome strengthened Bulgaria’s position and pressured the regional powers to regularize the new status.
The Ottoman Empire and the Principality of Bulgaria, in an ambassadorial setting involving the great powers, reached the Tophane Agreement. It recognized the Prince of Bulgaria as governor-general of Eastern Rumelia, giving legal form to the unification created in 1885. By 1886, this helped close the first major cycle of post-Berlin border disputes—even as deeper tensions in the Balkans continued.
Treaty of Berlin and its regional consequences in the Balkans (1878–1886)