The last Abbasid Caliph at Cairo , al-Mutawakkil III , was taken into custody and was transported to Istanbul , where he reportedly surrendered the Caliphate to Selim I. According to Barthold , the first time the title of `` Caliph '' was used as a political instead of symbolic religious title by the Ottomans was the peace treaty with Russia in 1774 . The last Abbasid Caliph at Cairo , al-Mutawakkil III , was taken into custody and was transported to Constantinople , where he reportedly surrendered the Caliphate to Selim I. According to Barthold , the first time the title of `` Caliph '' was used as a political instead of symbolic religious title by the Ottomans was the peace treaty with Russia in 1774 .