Allied Forces were victorious and occupied Constantinople, after which the Ottoman government collapsed. The Treaty of Sèvres, August 10, 1920 confirmed the dismemberment of the Ottoman Empire. Government of the Grand National Assembly Following the armistice, Mustafa Kemal Atatürk formed a Government in Ankara and the Turkish War of Independence against the Allies ensued. Outside of a small area surrounding Constantinople, Turkey was controlled by the Ankara Government and is referred to philatelically as "Turkey in Asia" or "Anatolia". This eventually led to the Treaty of Lausanne, July 24, 1923, which supplanted the Treaty of Sèvres. From 1920 to 1922, small stocks of old postage stamps were overprinted after which a number of large revenue stamps with intricate designs and without Western lettering were handstamped for validation as postage. Passer has stated that the study of the stamps of this period "is very difficult, for there are no reliable official records of the actual dates of their issue, or of the length of time for which they were used, and but few genuine letters with clear dates are available." The Republic of Turkey On 1 November 1922, the National Assembly, led by Mustafa Kemal, abolished the Sultinate and the last Sultan, Mehmed VI abdicated and fled the country. Turkey was declared a republic on 28 October 1923. The republic's first stamp issue was a definitive series depicting a star and crescent, somewhat reminiscent of the Duloz issue. This issue marked the end of the use of the Tughra which had appeared as a design element in most of Turkey's stamps from 1863 to 1922. The first republic issue was followed by an issue commemorating the Treaty of Peace at Lausanne, and other issues depicting national scenes and Mustafa Kemal. From the late 1920s up to 1940, Turkey overprinted a number of stamps to commemorate events such as exhibitions or the opening of a railroad. In 1931, Turkey began a new stamp issue in a more contemporary style depicting Mustafa Kemal. Mustafa Kemal would continue to be a common subject of Turkey's stamps thereafter. In the following decades, Turkey's stamp production became more varied, producing colorful stamps with a great diversity of images including scenes of the country, archeological sites, famous Turks, native flora and fauna, and folk costumes, to name just a few. Up to 1937, all of Turkey's stamps had been printed by either engraving or typography. In 1937,