 On 24 September 1841, Gregory XVI appointed Geissel coadjutor to the Archbishop of Cologne; and on 4 March 1842, he entered upon the administration of the archdiocese.When Clemens August died (19 October 1845), Geissel succeeded him, and was enthroned as archbishop, 11 January 1846.Finally, Pope Pius IX created him cardinal, 30 September 1850.