Following these events the Allied victors in World War I authorized the occupation of Smyrna, which still had many Greek inhabitants, by Greece in May 1919. This led to the Greco-Turkish War of 1919–1922, the subsequent defeat of Greece, and the Treaty of Lausanne in 1923. That treaty contained a protocol, the Population exchange between Greece and Turkey, which barred permanently the return of any prior Greek Orthodox refugees to their homes in Turkey (including the previous Livissi refugees) and required that any remaining Orthodox Christian citizens of Turkey leave their homes for Greece (with an exception for Greeks living in Istanbul).