When Greek Prime Minister Kyriakos Mitsotakis and Turkish President Recep Tayyip Erdogan met earlier this month at the NATO summit in Lithuania, they agreed to strengthen bilateral relations between their two countries.

Given the tension between Greece and Turkey in the recent past, this is no small thing. Over the past few decades, these former archenemies have gradually become mere neighbors — an outcome due in no small part to the Treaty of Lausanne, which was signed a century ago.

To understand the significance of this treaty not only for Greece and Turkey, but also for the wider eastern Mediterranean region as a whole, it is important to go back 570 years.

The fall of Constantinople: A Greek national trauma

In 1453, Constantinople (modern-day Istanbul), the capital of the Byzantine Empire, was captured by the Turks of the Ottoman Empire. For the Greeks, the fall of Constantinople, which marked the end of its political dominance in the region, became an historical trauma that resonates to the present day.

From that point on, the Greeks — like all other peoples in the Balkans — lived under Ottoman rule. The Greeks were the first to seek independence, establishing the modern Greek state in 1830 after a successful uprising.

Greece's 'Megali Idea'

In the late 19th century, many Greeks were inspired by the "Megali Idea" the ("Great Idea"): The conquest of Istanbul and the resurrection of the Byzantine Empire. Fueled by this idea, Greece attacked the Ottoman Empire in 1897 and suffered a stinging defeat.

The tables turned at the end of the Balkan Wars in 1913 when Greece annexed the regions of Macedonia, Epirus and Thrace.

The bitter fight for Smyrna

With the Treaty of Sevres (1920), the victorious Entente Powers of World War I sought to impose tough conditions on the defeated Ottoman Empire. The city of Smyrna (Izmir) was assigned to Greece. Smyrna was a liberal, cosmopolitan trading city with a large Greek community.

In October 1920, Greek Prime Minister Eleftherios Venizelos commanded the Greek Army to advance on Ankara. But the troops were poorly supplied and were soon surrounded by Turkish troops led by Mustafa Kemal Ataturk. The Greeks fled, and Smyrna went up in flames, with a heavy loss of life.

Ownership of the islands settled

In 1923, the Treaty of Lausanne replaced the Treaty of Sevres, which had never actually been ratified. It settled the issue of borders and the status of many islands in the Aegean.

Turkey accepted the treaties from 1913 that assigned several islands (including Lesbos, Chios and Samos) to Greece and ceded its rights to the Dodecanese, which were occupied by Italy during the Second World War. The islands of Bozcaada and Gokceada were assigned to Turkey.

Population exchange after the borders were drawn

The Lausanne Treaty defined both countries' national borders, which remain the same to this day, with the exception of one change in 1939, when Hatay elected to become a Turkish province.

After the signing of the treaty, there was an exchange of populations along religious lines between Greece and the nascent Republic of Turkey: Over 1 million Orthodox Christians left Turkey for Greece; 500,000 Muslims left Greece for Turkey.

The Treaty of Lausanne also regulated the rights of minorities and defined non-Muslims living in Turkey as minorities. The Turkish community in Western Thrace in Greece was also given minority status.

The treaty that paved the way for modern Turkey

For Turkey, too, the Treaty of Lausanne is of great significance. In stark contrast to the Treaty of Sevres and the Armistice of Mudros, which were seen as "documents of the collapse" of the Ottoman Empire after World War I, it is seen as the document that laid the foundation for the modern Turkish Republic.

The treaty ended the state of war between the Entente Powers and Turkey, which began with World War I and lasted about 10 years. The last Entente troops left Istanbul in October 1923.

On October 13 of that same year, Ankara officially replaced Istanbul as the capital of the country, and on October 29, the Turkish Republic was declared, followed by the abolition of the sultanate and the caliphate.

Political and economic sovereignty

Although the Lausanne Treaty imposed a number of armament and military restrictions relating to the straits between the Mediterranean and the Black Sea, the Montreux Convention, which was signed on July 20, 1936, restored Turkey's full sovereignty over the Dardanelles, the Sea of Marmara and the Bosporus.

The Treaty of Lausanne was also significant for another reason: It completely did away with what were known as the Capitulations of the Ottoman Empire, contracts concluded by the Ottoman Empire and Western States that granted privileges to these states. Although Turkey continued to pay the debts of the Ottoman Empire until 1954, the Treaty of Lausanne gave it economic independence.

Conspiracy theories and the way forward

The significance of the Treaty of Lausanne is still debated in some circles and is often the focus of several conspiracy theories in Turkey. The two most important of these are that the treaty contains secret clauses that were never made public and that the treaty will end 100 years after it was signed. Although these two claims have been refuted by reputable historians in Turkey, they occasionally crop up in political debates.

Although Greece and Turkey have not gone to war since the signing of the Treaty of Lausanne, there has been no shortage of tension and strife between the two countries in the intervening period.

Greek Prime Minister Kyriakos Mitsotakis has said that he would like the International Court of Justice in The Hague to resolve any disagreements between the two nations. It would appear to be a reasonable approach, particularly as there is no viable alternative.

In a widely discussed strategy paper dating from January 2023, the Athens-based political scientists Athanasios Platias and Konstantinos Koliopoulos wrote that while "Greece and Turkey are not at war, there is no comprehensive peace. (...) and yet even in an environment so charged with tension, there is no shortage of common interests that lead to cooperation."

This article was adapted from the German by Aingeal Flanagan