Although the CUP had worked with the Armenians to reinstall constitutional monarchy against Abdul Hamid II , factions in the CUP began to view the Armenians as a fifth column that would betray the Ottoman cause after World War I with nearby Russia broke out ; these factions gained more power after the 1913 Ottoman coup d'état . The first major offensive the Turks undertook in World War I was an unsuccessful attempt to drive the Russians from the portion of Western Armenia they had taken in the Russo-Turkish War of 1877 . After the failure of this expedition , the CUP 's leaders , Enver , Djemal , and Talaat , were involved in ordering the deportations and massacres of 1 and 1.5 million Armenians in 1915 &ndash; 1916 in what became known as the Armenian Genocide . After World War I and the signing of the armistice of Mudros , the leadership of the Committee of Union and Progress and selected former officials were court-martialled with/including the charges of subversion of the constitution , wartime profiteering , and the massacres of both Armenians and Greeks . The court reached a verdict which sentenced the organizers of the massacres , Talat , Enver , Cemal and others to death
Greeks
Greek genocide
1913 Ottoman coup d'état