Convention of Constantinople (1881)

The Convention of Constantinople was signed between the Kingdom of Greece and the Ottoman Empire on 2 July 1881, resulting in the cession of the region of Thessaly and a part of southern Epirus (the Arta Prefecture) to Greece.

Greece had remained neutral during the Russo-Turkish War of 1877–78, based on assurances by the other Great Powers that her territorial claims on the Ottoman Empire would be considered after the war. At the Congress of Berlin in 1878, Greece's claims were considered in the Thirteenth Protocol of 5 July 1878, whereby Greece gained not only Thessaly (the Ottoman Sanjak of Tirhala) but also much of Epirus. The Ottoman government, however, refused to implement the protocol's terms, leading Greece and the Empire to the verge of war. In the end, the Great Powers applied pressure on Greece to reduce her claims.

On 24 May 1881, the Great Powers and the Ottoman Empire signed a treaty which finalized the new Greco-Turkish border, leading to the incorporation of most of Thessaly (except the Elassona area) and of the area around Arta into Greece. Among other measures, Greece in turn pledge to respect the religious identity and autonomy, as well as the possessions of the sizeable Muslim population in Thessaly (including the private possessions of the Sultan and the Ottoman imperial family). The treaty was ratified by Greece and the Ottoman government on 2 July, when it was signed by the Greek ambassador to Constantinople, Andreas Koundouriotis (), and Mahmud Server Pasha (), President of the Ottoman Council of State ().

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