 Shortly thereafter he was expelled from Tehran to Baghdad , in the Ottoman Empire ; then to Constantinople ( now Istanbul ) ; and then to Adrianople ( now Edirne ) . In 1863 , at the time of his banishment from Baghdad to Constantinople , Bahá 'u'lláh declared his claim to a divine mission to his family and followers . Tensions then grew between him and Subh @-@ i @-@ Azal , the appointed leader of the Bábís who did not recognize Bahá 'u'lláh 's claim . Throughout the rest of his life Bahá 'u'lláh gained the allegiance of most of the Bábís , who came to be known as Bahá 'ís . Beginning in 1866 , he began declaring his mission as a Messenger of God in letters to the world 's religious and secular rulers , including Pope Pius IX , Napoleon III , and Queen Victoria . 
