The Treaty of Lausanne, settling the boundaries of modern Turkey, is signed in Switzerland by Greece, Bulgaria and other countries that fought in World War I.

The Treaty of Lausanne is a peace treaty negotiated during the Lausanne Conference of 1922–1923 and signed in the Palais de Rumine in Lausanne, Switzerland, on 24 July 1923. The treaty officially resolved the conflict that had initially arisen between the Ottoman Empire and the Allied French Republic, British Empire, Kingdom of Italy, Empire of Japan, Kingdom of Greece, Kingdom of Yugoslavia, and the Kingdom of Romania since the outset of World War I. The original text of the treaty is in English and French. It emerged as a second attempt at peace after the failed and unratified Treaty of Sèvres, which had sought to partition Ottoman territories. The earlier treaty, signed in 1920, was later rejected by the Turkish National Movement which actively opposed its terms. As a result of Greek defeat in the Greco-Turkish War, Turkish forces recaptured İzmir, and the Armistice of Mudanya was signed in October 1922. This armistice provided for the exchange of Greek-Turkish populations and allowed unrestricted civilian, non-military passage through the Turkish Straits.