Epilogue, p.666, f.1

"The Caliphate began with the election of Abu-Bakr in A.D. 632 and lasted until A.D. 1258, when Hulagu Khan sacked Baghdad and put Mu'tasim-Bi'llah to death. For nearly three centuries after this catastrophe the title of Caliph was perpetuated in Egypt by descendants of the House of Abbas who lived under the protection of its Mameluke rulers, until in A.D. 1517 Sultan Salim, the Osmanli, having conquered the Mameluke dynasty induced the helpless Caliph to transfer to him the title and insignia." (P. M. Sykes' "A History of Persia," vol. 2, p. 25.)