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, Cemal, and Talaat, were involved in ordering the deportations and massacres of 1 and 1.5 million Armenians in 1915–1916 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.