The First Balkan Alliance () was a system of agreements concluded by the Principality of Serbia in the period of 1866–68 to unite the nations of the Balkans in a common struggle against the Ottoman Empire. The plans for forging this alliance were based on the organization of a major general uprising, as opposed to individual uprisings by the various ethnic groups in Ottoman territory. According to the plans, the Albanians would begin the uprising, followed by Serb and Greek volunteers and finally and simultaneously by the regular armies of Serbia and Greece. According to the plans and agreements, after a successful war against the Ottomans, the Balkan nations would establish a united federation.
This alliance was conceived as part of one of various proposals for a Balkan federation, planned as a buffer zone between East and West. Members of the First Balkan Alliance were Serbia, Montenegro, Bulgarian revolutionary committees, the Croatian People's Party, Greece and Romania. The major role in establishing of the First Balkan Alliance was played by Serbia, under Prince Mihailo Obrenović and Prime Minister Ilija Garašanin.
Background
In the middle of the 19th century, most of the territory of Balkans was still part of the Ottoman Empire, with several newly established independent or autonomous entities like Serbia, Greece, Bulgaria and Montenegro. All of them struggled to expand their influence and territory at Ottoman expense. Their intention was strongly opposed by Austria who opposed development of Balkan nations and revolutions in the Ottoman provinces of Europe (Rumelia). Austria's position was based on its own expansionistic plans on the Balkans and on fear that a strong Slavic state would attract Slavic citizens of the Austrian Empire. After defeat in the war against France in 1859 and against Prussia in 1866, the influence of Austria weakened.
Napoleon III was the champion of the idea of Balkan nationalism and fostered Serbia and Greece to build alliances and undermine Ottoman influence in the region. France planned to resolve the Balkan Eastern Question through gathering of all Balkan Slavic people, including Bulgarians, around Serbia as their pillar. This was not only informally suggested by French diplomats since 1861, but also formally proposed in Saint Petersburg in 1867. The establishment of Balkan alliances was supported and aided by Russia because it corresponded with its policy of promoting Balkan unity.
Alliance agreements
The establishment of the Balkan alliance was campaigned by Prince Mihailo Obrenović of Serbia. To establish the First Balkan Alliance, the Principality of Serbia signed a series of contracts in the period 1866–68. The first contract was signed with Montenegro in 1866. The next contract was signed in autumn of 1866 with the People's Party in Croatia-Slavonia led by Catholic bishop Josip Juraj Strossmayer. This contract was followed by contract with Bulgarian Revolutionary Secret Society in 1867, with Greece in 1867 and with Romania in 1868.
Montenegro
The agreement between Serbia and Montenegro was signed on 5 October 1866 in Cetinje. According to the agreement, Serbia and Montenegro would act as an unified Serb country.