The Treaty of Vöslau, signed on August 26, 1867, was proposed by Greek Foreign Minister Charilaos Trikoupis and was signed by Petros Zanos and Prince Mihailo Obrenović III of Serbia. It was the only alliance signed between Greece and another country during the 19th century. It was also the first attempt at an alliance between Balkan against the Ottoman Empire. The two states agreed on the lands each of them would occupy following a successful war against the Ottoman Empire.
The treaty never came into effect, as Prince Mihailo Obrenović III was murdered soon afterwards. [1]