The photographs are compelling: Greek Orthodox Christians are gathered in small groups on the Aegean coast of what is now Turkey, wearing too much clothing for the hot day, whatever possessions they could carry sitting at their feet, their faces drawn with worry as they stare at the water, awaiting the ships that would take them to Greece. They were being expelled from Anatolia, where their ancestors had lived and died and worked and prayed for so many centuries that most claimed no other homeland. These Christians followed a patriarch who had resided in Constantinople/Istanbul since the year 330 and whose massive cathedral, Hagia Sophia, had already become a major tourism site. For centuries, the community had regulated prayer, education, taxation and communal life under the ruling Ottoman sultans. The status of Orthodox Christians, like those of the other Ottoman millets (Armenian, Syriac and Catholic Christians, as well as Jews) began to change dramatically as increasingly powerful European empires intervened in Ottoman territories, claiming to be “protecting minorities.” Still, despite anti-Armenian violence at the end of the 1800s, it was only with the Balkan wars at the beginning of the twentieth century that the Ottoman regime began to define Greek Orthodox Christian Ottomans as enemies. And it took a Greek invasion of Anatolia in 1919 to set in motion the catastrophic events that would result in the expulsion of these Christians standing on the Aegean shore.
In addition to thousands of refugees who had already flooded into Ottoman territories as a result of World War I, the Bolshevik revolution and the counter-revolution, a new wave of desperate people had emerged as a result of Greece’s invasion. That offensive, encouraged by British Prime Minister David Lloyd George, had been bloody from the start and brought out what seemed to be ambivalence toward the Ottoman sultan among his Greek Orthodox subjects. The local Greek Orthodox archbishop blessed the arriving Greek soldiers. Worse, when the first Greek soldiers advanced on government headquarters in Smyrna/Izmir, local Greek Orthodox looted the city.  Although Greek Orthodox Christians had lived in Asia Minor throughout the Ottoman period, these kinds of actions confirmed for some Ottoman leaders that their own “Greeks” could not be trusted. Indeed, the loss of significant territory during the Balkan wars (1912-1913), and the decision of Ottoman Christians there to side with the Ottomans’ enemies, convinced many at the Sublime Porte that the survival of the state required the marginalization (or expulsion) of Christians. 
The Ottoman government had acquiesced to the 1918 Mudros Armistice, which granted the Allies the right to occupy Ottoman territory “in case of disorder,” as part of ending their involvement in World War I. But the Greek invasion proved too much to accept, the last straw for those appalled by the punitive terms of the 1920 Sèvres Treaty that the Allies were imposing on the defeated Ottomans. Within months, an incipient nationalist movement engaged the invaders on the battlefield, and began organizing congresses in eastern Anatolia that defied Allied plans. Fury at the Greek invasion and mistreatment of Turks elicited atrocities perpetrated by Turkish nationalist armies; hundreds of thousands of Greek Orthodox Ottoman subjects began fleeing oncoming nationalist troops and flooding into Ottoman cities, homeless, destitute and, in many cases, exhausted from their arduous journey. Questioning the loyalty of Greek Orthodox Ottomans, Turkish nationalist forces rounded them up and deported them to labor camps, from which few returned. The plight of these refugees captured the international media of the day, displacing the previous images of Muslim victims of the invading Greek armies.
For Turkish nationalist leaders in Ankara, any Ottoman subject who embraced the Greek Orthodox faith had become suspect. As the Turkish delegate to the Mixed Commission for the Exchange of Greek and Turkish Populations would later explain, “The Turkish government desires to suppress the Greek irredentism in Turkey.”  Religious practice had become transformed into national identity.
But the initial request for an exchange of populations came from Greek Prime Minister Eleftherios Venizelos, through the auspices of Fridtjof Nansen, the League of Nations high commissioner for refugees. In the letter he submitted to the Council of the League of Nations on October 16, 1922, Venizelos proposed a “compulsory exchange of Greek and Turkish populations,” and asked Nansen to make the necessary arrangements. The Allied high commissioners in Istanbul (British, French, Italian and Japanese) had reinforced this request: Nansen was urged to arrange “for the reciprocal emigration of the racial minorities of the two countries.”  Thus it was that the League of Nations came to consider ethnic cleansing the best option for dealing with the refugee crisis.
Nansen described the issue as “of extreme economic and social importance to the countries of the Near East, and also of great importance for the peace of the world.” He was frustrated, however, by his inability to arouse interest on the part of the Turkish nationalist leadership. Hamid Bey, the nationalists’ representative in the Ottoman capital, could offer no commitment to Turkish support for an exchange or even a meeting with the new government in Ankara, which was still waging a war. Mustafa Kemal’s reply was hardly promising: “The exchange proposed by Dr. Nansen is agreeable in principle. Nevertheless, the matter must be considered with the Government. As it is impossible for me under present conditions to wait in any one town it is unfortunately not possible for me to fix a meeting place.” When Hamid Bey finally did respond, he informed Nansen that he could negotiate only “on the basis of a total and enforced exchange of populations, from which the population of Constantinople would not be exempted.” With Hamid Bey leaving for new treaty negotiations at Lausanne, however, all discussions were at an impasse. 
Religion Into Race
The exchange of populations was among the first topics to be discussed when negotiations began in November 1922 to revise the never-ratified 1920 Sèvres Treaty. Fridtjof Nansen was convinced that exchanging the “Greeks” of Turkey for the “Turks” of Greece would provide benefits to both countries. Many people “of the Greek race” (in Nansen’s classification) had already left their homes and become refugees in Greece, Nansen wrote, while others remaining in Turkey “will very probably desire to transfer their domicile to Greek territory.” At the same time, “a great many persons of Turkish race domiciled on Greek territory will very probably desire to transfer their domicile to Turkish territory.” Such mass population movements needed careful regulation, without which they would result in “grave economic and administrative difficulties.” 
Out of a combination of concern for the safety of “minorities,” conviction that unlike people simply could not get along, desperation in the search for resources for the growing mass of impoverished refugees, and anxiety about possible Bolshevik inroads into the devastated population, the League of Nations promulgated the Convention Concerning the Exchange of Greek and Turkish Populations. Article 1 reads,
As from the first of May, 1923, there shall take place a compulsory exchange of Turkish nationals of the Greek Orthodox religion established in Turkish territory, and of Greek nationals of the Moslem religion established in Greek territory. These persons shall not return to live in Turkey or Greece respectively without the authorisation of the Turkish Government or of the Greek Government respectively. 
Nansen’s “races” had been defined by faith tradition: Muslims were henceforth “Turks” and Greek Orthodox Christians became “Greeks.” Greek-speaking Muslims whose ancestors had resided, procreated, traded and worshipped within the new borders of Greece were deemed to be Turks; half a million “Turks” were relocated to their “own” nation, the just-created Republic of Turkey, where they could not even speak the language. At the same time, some 1.5 million Turkish-speaking Greek Orthodox Christians — whose ancestors’ lives within the area now defined as Turkey predated the Roman Empire — were now forcibly relocated to Greece. Religion had become racial identity as families were uprooted, neighborhoods destroyed and trade networks eradicated.
Nationalist leaders in Ankara and Athens agreed on the importance of the exchange. Turkish nationalists, burned by losses during the Balkan wars and the Greek invasion, feared the irredentism prevalent among Venizelos’ followers (and David Lloyd George), who supported the Great Idea of an expansionary Greece to be based in Constantinople. Greek leaders desperately needed the resources that would be made available by expelling Muslims; they could use Muslim homes and property to settle refugees. Moreover, both elites were interested in creating ethno-religiously homogenized nation-states on the “modern” European model.
These goals were not always shared by prominent members of the communities in question. The long letter dated April 14, 1920, signed by the archbishop of Trebizond/Trabzon, the president of the Pan-Pontic Congress and the president of the National League of the Euxine Pontus at Paris petitioned not for expulsion and exclusion, but for decentralization and local control over the Greek Orthodox population on the eastern Black Sea coast of Anatolia.  Even in 1923, Greek juridical expert and staff member of the League of Nations Political Section Thanassis Aghnides noted, “I am in a position to confirm…that the Greeks are not particularly anxious to get rid of the Turks living in Greece. However, the Greek Gmnt. [sic] will have to ask the Turks in question to leave Greece so that the Greek refugees may find shelter during the approaching winter. Mons. Politis told me a few days ago that the Greek Gmnt. is in this matter bound to yield before the inexorable necessities of the situation.” 
Although the League of Nations presumed that the identities of the people to be exchanged would be self-evident, assigning people affiliations as “Turks” and “Greeks” proved to be a challenge. Turkey’s representative to the Mixed Commission pointed out that Arabic speakers also adhered to the Greek Orthodox faith, and that Russian- and Serbian-speaking Ottomans would also be eligible for exchange since their faith was the sole criterion. The Greek delegation insisted that people being exchanged must be both Greek and Orthodox. For the Turks, however, “Greek Catholics” were also liable to irredentism, and they, too, should be eligible for exchange, while Arabic-speaking and other Orthodox Christians were not so susceptible. 
Defining “Turks” proved to be challenging as well. The Albanian government complained to the League of Nations that Albanian Muslims were being wrongly defined as Turks and forced to relinquish their property and leave for Turkey. In response, the League sent commissioners to determine the identities of the people living in the Albanian-Greek border areas. On June 12, 1924, the Mixed Commission provided instructions for determining who would be subjected to forced migration. The most important criterion would be place of origin: If the person in question originated from Turkey, this information would be “sufficient to warrant the decision that the person concerned should be included in the exchange.” Language should be considered a “basic factor,” and “national consciousness, when clearly manifested, should constitute a factor of the highest importance.” All other factors are “of merely relative importance” and should be considered “subsidiary to the main factors” of origin, language and national consciousness. 
Indeed, the delegation that traveled to the disputed regions found that these criteria did not create a taxonomy for distinguishing Turks from non-Turks. Language was not very important: “As the delegation was able to observe in Macedonia, the inhabitants of a district, being intermingled with other peoples, have had, in order to facilitate their relations with these peoples, to learn and use more than one language, so that the very conception of a mother-tongue has often ceased to exist.” “Habits and customs” were also of dubious value in determining people’s affiliation: Religious rituals were shared by Muslims from Turkey and Albania, and local customs were shared by Muslims and Christians. In the end, the delegation recommended that a body be created very soon to decide the status of people who were to be exempted from the exchange, and that they would provide non-transferable certificates to those “Albanian” Muslims allowed to remain in Greece. Although “one of the main factors” to be considered, national consciousness “cannot, in view of the history of the countries in question, be very accurately established.” 
Turkish and Greek historians have agreed that the ethnicized religious identity mobilized by the population exchange consolidated a new kind of national solidarity. Moreover, the narratives of victimization, prevalent in both modern Greece and modern Turkey, certainly have compelling dimensions in creating a common enemy and a national “history.” As Anastasia Karakasidou points out, however, these collective “memories” obfuscate as much as they reveal. In the years before the Balkan wars, people worked together, lived as neighbors and depended on each other in a web of economic relationships. In the area of Macedonia on which she focuses, “the cultural field of late Ottoman-era Guvezna and the neighboring settlements with which its inhabitants traded was both fluid and diverse, with shifting boundaries of identity, interest and solidarity.” These complex relationships were supplanted by a nationalist history that “emphasized the collective destiny of the nation, and collapsed the personal experiences and memories of individuals with those of the new national group.” Although their integration into the new Greece strengthened the narrative, and the refugees willingly took on their new Greek identity, they were unable entirely to forget or elide their customs and heritage; they continued for decades to be referred to by others as “refugees,” and to refer to the place they had left as their “country.” 
Despite the use that later governments have tried to make of the Greek-Turkish population exchange as a prototype, the League of Nations’ ethnic cleansing was devastating and traumatic for its coerced participants. Oral history projects and NGO reports are replete with narratives of the enormous toll the events had on those expelled from their homes, as evident in the remarkable traveling exhibit based on Bruce Clark’s 2006 book, Twice a Stranger.  One of the great ironies of the exchange was that it took place at the very same time that the League of Nations was debating a minority treaty to impose on Turkey, a document that would be similar to the minority treaty imposed on Poland in 1919 and many states over the following years. These treaties promised protection for minorities and guaranteed them safety, security and recognition for their languages, cultures and properties, provisions that were simultaneously being abrogated by the League’s own project of ethnic cleansing of “Greeks” and “Turks.” 
The Convention Concerning the Exchange of Greek and Turkish Populations resulted from a particular historical context: As a result of territorial losses at the hands of Christian-dominated powers, Ottoman leaders became suspicious that Ottoman Christians were harboring irredentist aspirations, suspicions exacerbated by Great Power interventions and mobilized by Turkish nationalist leaders who wanted to stamp their state-in-becoming in the mold of exclusionary European-style nation-states. The brutal ethnic cleansing that resulted, executed by an international organization devoted to peacemaking, resulted in the codification of religion-as-difference and the consolidation of near religious uniformity in formerly diverse areas. According to Mark Mazower, for example, Salonika exemplified a “multi-confessional, extraordinary polyglot Ottoman world — as late as the First World War, Salonican bootblacks commanded a working knowledge of six or seven languages.”  The remarkable linguistic, religious and cultural wealth that had characterized international cities like Salonika has given way to monocultural nation-state formations.
Just as the population exchange was historically contextual, it was also socially constructed. Ignoring the material conditions which had resulted in the loss of territory during the wars, privileging religious identity over class or location, and creating polarizing narratives during a time of war, the leaderships inaccurately insisted that identity determined political goals, that religion could predict earthly loyalty, and that security could only come with the creation of a purified populace. Despite centuries of alternative realities, the new ideologies of the nation-state required a new form of “sectarianism” whose manifestation was, simply, evil.
 Andrew Mango, From the Sultan to Atatürk: Turkey (London: Haus, 2009), pp. 62-63. Over the course of the ensuing war, the atrocities carried out by various forces in Anatolia were documented and described by international agencies, including the horrific events investigated by the Inter-Allied Commission. Reports on Atrocities in the Districts of Yalova and Guemlek and in the Ismid Peninsula: Inter-Allied Commission of Enquiry Into Atrocities in Yalova and Guemlek, http://www.archive.org/details/reportsonatrocit00interich.
 Taner Akçam, The Young Turks’ Crime Against Humanity: The Armenian Genocide and Ethnic Cleansing in the Ottoman Empire (Princeton, NJ: Princeton University Press, 2012).
 Stephen P. Ladas and Bureau of International Research of Harvard University and Radcliffe College, The Exchange of Minorities: Bulgaria, Greece and Turkey (New York: Macmillan, 1932), p. 279.
 Annex A to “Report by Dr. Nansen, Part 1,” November 15, 1922, League of Nations Archives, Geneva, Switzerland (hereafter SDN) S 389.
 “Report by Dr. Nansen, Part 1,” November 15, 1922, SDN S 389.
 Annex A to “Report by Dr. Nansen, Part 1,” November 15, 1922, SDN S 389.
 The treaty is available at: treaties.un.org/doc/Publication/UNTS/LON/Volume%2032/v32.pdf, p. 77.
 SDN R 1617.
 Minute dated September 19, 1923, SDN R 1685.
 Ladas and College, p. 378.
 “Instructions Issued to the Competent Sub-Commissions for the Exemption from Exchange of Moslem Greek Subjects of Albanian Origin,” June 17, 1924, enclosed in Ekstrand to Drummond, June 19, 1924, SDN S 370.
 “General Report of the Delegation of the Mixed Commission Entrusted with the Investigation of the Albanian Question,” June 2, 1924, enclosed in Ekstrand to Drummond, June 19, 1924, SDN S 370.
 Anastasia Karakasidou, Fields of Wheat, Hills of Blood: Passages to Nationhood in Greek Macedonia, 1870-1990 (Chicago: University of Chicago Press, 1997), pp. 12, 25, 148-149.
 Bruce Clark, Twice a Stranger: The Mass Expulsions That Forged Modern Greece and Turkey (Cambridge, MA: Harvard University Press, 2006).
 “Moslems of Albanian Origin in Greece, Report by the Spanish Representative,” 1924, adopted by the League of Nations Council, SDN S 370.
 Mark Mazower, Salonica, City of Ghosts: Christians, Muslims and Jews, 1430-1950 (London: HarperCollins, 2004), p. 12.