 He encouraged popular missions, introduced religious orders and congregations into the archdiocese, instituted the Perpetual Adoration, and stimulated devotion to the Blessed Virgin by celebrating with unusual splendour the declaration of the dogma of the Immaculate Conception.He convoked the German episcopate to the Würzburg Bishops' Conference in 1848; in 1860 he held a provincial council at Cologne.Geissel lived long enough to see Cologne Cathedral finally completed and dedicated in October, 1863.