Greece–Türkiye border

A land bridge between continents

In 1964 the US Geographer wrote that few boundary regions had been fought over as hard or as long as this one, a land bridge between Europe and Asia.^[1] Its focal point is Edirne (Adrianople), founded by the Romans as Hadrianopolis where the Arda, Maritsa and Tunca rivers meet. It was the Ottoman capital a century before the conquest of Constantinople in 1453.^[1]

Before the First World War, Eastern Thrace was a mosaic of Turks, Greeks, Bulgarians, Armenians, Jews and others. A 1912 estimate put Turks at two-thirds of its people and Greeks at a quarter.^[1] The Balkan Wars moved the Ottoman frontier twice: in May 1913 to a straight line from the Black Sea to Enez, and after the Second Balkan War back to the Maritsa, then against Bulgaria.^[1]

From Sèvres to Lausanne

The Treaty of Sèvres, signed by the Ottoman government on 10 August 1920, would have left Turkey only Constantinople in Europe. The nationalist government in Ankara refused to recognise it.^[1] Greek troops had landed at Izmir (Smyrna) in May 1919, and Mustafa Kemal led three years of war that ended with the Greek army driven out.^[1]

The armistice of Mudania, signed on 11 October 1922, had Greece evacuate Eastern Thrace and restored it to Turkey as far as the Maritsa. Greece signed three days later.^[1] The Treaty of Lausanne, signed on 24 July 1923 after months of argument over Turkish claims west of the river, fixed the line on the Maritsa. Opposite Edirne, Turkey received a bridgehead on the west bank containing a stretch of railway, in settlement of its reparation claims against Greece.^[1]

The war also ended the old mix of peoples. The Mudania armistice, confirmed at Lausanne, excluded all Greeks from Eastern Thrace apart from Constantinople.^[1] In 1960 Western Thrace, on the Greek side, still had about 95,000 Muslims, among them about 65,000 Turks.^[1]

The river line

A boundary commission set up by the treaty marked the line in 1925–26, and its conclusions were signed in Athens on 3 November 1926.^[1] From the Bulgarian tripoint the border follows the middle of the Maritsa or its main channel. At the Arda confluence it turns up the Arda for 0.6 of a mile, then leaves the water and runs 6.7 miles over land between markers 2 and 23, enclosing the Turkish bridgehead, then returns to the river. Near the sea the Maritsa splits in two, and the border takes the eastern, main branch to the Aegean.^[1]

The valley is broad, flat and prone to floods, and the Greek bank is marshy almost the whole way to the sea. The delta between the two branches is impassable in winter and spring.^[1] In 1964 the Geographer knew of no disputes along the line.^[1]

“Other than a distance of 6.7 miles of land boundary delimiting a small enclave west of the Maritsa River opposite Edirne (Adrianople), the entire boundary follows rivers.”^[1]

Migrants and a fence

In late February 2020 President Erdoğan’s government said Türkiye would no longer stop migrants and refugees from crossing into the EU, and thousands gathered at the border. At the Kastanies (Pazarkule) crossing near Edirne, Greek police fired tear gas at crowds trying to break through the fence, and Turkish police fired tear gas back.^[2]

Greece has since extended its fence along the Evros. A central section begun in 2023 was largely finished in early 2025, with about 5 km left incomplete, mostly near Soufli. According to Kathimerini, Greek military maps put those spots on the Greek side and Türkiye says they are Turkish, a disagreement partly due to the river shifting its course. Greece began digital mapping of the border in 2024, replacing the 1926 surveys, and found small discrepancies. When Greece decided to finish the fence there, Türkiye delivered a formal protest in 2026.^[3]