[2] On 13 October 1837, conscious that he had not long to live, Yohannan Hormizd designated as coadjutor and 'guardian of the throne' Gregory Peter di Natale, metropolitan of Gazarta, presumably with the intention of excluding his nephew Eliya from the patriarchal dignity.
The main reason for the Vatican's intervention was to ensure that the hereditary principle, first introduced into the Church of the East in the fifteenth century, would play no part in the selection of the next patriarch.
The bull mentioned Yohannan Hormizd's growing infirmity and the desirability of avoiding inconvenience and harm should the patriarchate suddenly become vacant.
[3] The bull of appointment arrived in Mosul after the death of Yohannan Hormizd, thus Nicholas Zaya became patriarch in 1839 and was confirmed by the pope on April 27, 1840.
The Chaldean metropolitans Lawrent Shoa of Kirkuk, Basil Asmar of Amid, Joseph Audo of Amadiya and Mikha'il Kattula of Seert, angered that they had not been consulted in the choice of Yohannan Hormizd's successor, met in the spring of 1839 in an attempt to elect one of their number patriarch, but were unable to agree.
He began by directing Joseph Audo to leave Amid for Amadiya, so that he could properly administer his metropolitan province, but eventually agreed to let him reside at Alqosh.
Early in 1843 an attempt by Zaya to reform the church calendar by adopting the Western date for Easter aroused strong resentment among the Mosul Chaldeans, and provoked a movement, in which the Anglican missionary George Percy Badger was implicated, to depose him and replace him with Yohannan Hormizd's nephew Eliya.
Zaya and the French missionaries who supported him complained vigorously to the Turkish authorities, and wrote to the British embassy in Constantinople to protest at Badger's interference.
His opponents accused him of embezzling church funds, which he had in fact used to restore the monastery of Mar Giwargis near Mosul, and spread rumours, 'generally believed to be without foundation', according to Badger, of immoral conduct.