On 19 November, Nestorius, anticipating the ultimatum which was about to be delivered, convinced Emperor Theodosius II to summon a general council through which Nestorius hoped to convict Cyril of heresy and thereby vindicate his own teachings. Theodosius issued a Sacra calling for the metropolitan bishops to assemble in the city of Ephesus, which was a special seat for the veneration of Mary, where the "theotokos" formula was popular. Each bishop was to bring only his more eminent suffragans. The date set by the Emperor for the opening of the council was Pentecost (7 June) 431.