Yohannan Hormizd himself wrote a polemical autobiography in Syriac, a fragment of which (breaking off in 1795) was translated into English by the Anglican missionary George Percy Badger and reproduced in his classic 1852 study of the Church of the East, The Nestorians and Their Rituals.

[3] His opponents responded with an equally intemperate history of the monastery of Rabban Hormizd under the headship of Gabriel Dambo of Mardin (1775–1832), which was published in a French translation by M. Brière in 1910 and 1911.

Neither can be trusted on matters of interpretation, but if read judiciously they shed valuable light on the politics of the Chaldean Church in the late eighteenth- and early-nineteenth centuries and provide a wealth of factual detail omitted in many accounts of this period.

Much of the recent scholarship on Yohannan Hormizd is in French or German, but convenient English summaries of his career were made by David Wilmshurst in 2000 and by Christoph Baumer in 2006.

Eliya XI had consecrated his nephew Ishoʿyahb a metropolitan in 1745 and had also bestowed upon him the traditional title natar kursya ('guardian of the throne'), thereby designating him his presumptive successor.

Earlier in the same year, however, Eliya had deposed Ishoʿyahb from his metropolitan rank, apparently alarmed by his ambition, and ordained the twelve-year-old Yohannan Hormizd, another nephew, as a deacon.

If his uncle had lived a few years longer, Yohannan's succession would probably have been assured, but the patriarch was among the victims of a plague which swept through the Mosul district in 1778, and died in the village of Alqosh on 29 April 1778.

The notables of Mosul, with the support of the Latin missionaries, deposed him and unanimously chose Shemʿon of Amid, the Chaldean metropolitan of Mardin (1758–88), as patriarch in his place.

Yohannan was elected patriarch in 1780, and his supporters bribed the governor of Mosul to use his influence to obtain a firman from Constantinople, granting him authority over both the Chaldean Christians and the Nestorians.

The Vatican's initial response was therefore to inform Raphael Terconuski, the superior of the Catholic mission at Mosul, that Yohannan Hormizd's profession of faith appeared to be satisfactory, but that his election was to be considered null.

In May 1790, on the advice of the missionaries, he consecrated his nephew Shemʿon metropolitan, and in August of the same year sent him to the Zibar district, where he converted the Nestorian villages of Arena and Barzane.

He was said, among other things, to have released a monk from his vows for a payment of 73 piastres, to have used liturgical books full of errors, to have visited families without a companion, and to have feasted in the house of a newly-wed couple.

He made another Catholic profession of faith on 7 April 1783 in an attempt to regain the sympathies of the missionaries, and to preserve the patriarchate within his family consecrated his nephew Hnanishoʿ metropolitan in 1784.

Yohannan punctiliously wrote to the Vatican for guidance, but as Rome was then under French occupation he did not receive a reply, and in 1798 consecrated the Indian priest Paul Pandari as a bishop for the Malabar Christians.

[16] Some years later Yohannan Hormizd faced another challenge to his authority from a Baghdad merchant named Gabriel Dambo, one of the most remarkable figures of the nineteenth century Chaldean church.

A Chaldean Christian born in Mardin in 1775, Dambo had made sufficient money by middle age to be able to retire from business, and he decided to devote the rest of his life to the service of the Church.

He paved the way by giving free lessons in Baghdad to young Chaldean Christians in Arabic, grammar, logic and rhetoric, and after winning a formidable reputation as a teacher and scholar moved to Mosul.

After a series of mutual recriminations, the Rabban Hormizd monks and the Catholic missionaries wrote jointly to the Propaganda calling for Yohannan's deposition, alleging that he was opposed to their order, that he incited the Kurds of Isma'il Pasha against them, and that he was endeavouring to lead the Chaldean proselytes back to Nestorianism.

Eventually he decided to seek a reconciliation with them, and a meeting was held on 20 February 1818 at Alqosh, attended by a hundred clergymen and notables, in which he agreed to apologise in writing for his misdeeds.

Three monks of the monastery of Rabban Hormizd were consecrated metropolitan bishops at Amid by Hindi in March 1825: the future patriarch Joseph Audo for Mosul, Lawrent Shoʿa for Baghdad, and Basil Asmar for ʿAmadiya.

Two other bishops perhaps consecrated on the same occasion, Mikha'il Kattula and Ignatius Dashto, were sent to Seert and Mardin, traditional sees of the Amid patriarchate, but the other three returned to their home villages north of Mosul; Basil Asmar to Telkepe, Lawrent Shoʿa to Tel Isqof and Joseph Audo to Alqosh.

In 1827, during the absence of the superior Gabriel Dambo in Rome, a number of monks in the monastery of Rabban Hormizd rebelled against its administrator Yohannan Gwera, who enjoyed the support of the metropolitan Joseph Audo.

Like Basil before him, however, he declined to trust his life to the good faith of Isma'il Pasha, and withdrew to Alqosh, where he continued to intrigue among the Chaldeans and with the local authorities of Mosul against Yohannan.

Gabriel Dambo was then in Rome, to lobby more effectively against his rival, and he and his supporters declared Coupperie's decision invalid and insisted that they would not accept Yohannan's authority unless he was absolved personally by the pope.

[21] Couperrie died shortly afterwards, and was succeeded as apostolic vicar by his assistant Laurent Trioche, who was consecrated a bishop for the purpose by Yohannan and the metropolitan Lawrent Shoʿa of Kirkuk on the Vatican's instructions.

[24] In spite of this account, it was presumably with the intention of excluding this nephew from being his successor that in 1837 Yohannan, aware that he had not long to live, designated Gregory Peter di Natale, metropolitan of Gazarta, as coadjutor and "guardian of the throne".

Gabriel Dambo was among the hundreds of East Syrians killed by the Kurds, and was succeeded as superior of the monastery of Rabban Hormizd by Yohannan Gwera.

A rumour spread that a new Latin apostolic vicar had been appointed in Rome and was now on his way to Mosul, and the patriarch's enemies temporarily came into line to make a good first impression on this important official.

[25] The patriarch now sent the metropolitan Gregory Peter di Natale to Mosul, accompanied by a priest named Andrew to represent the apostolic vicar Laurent Trioche, to inquire into the conduct of the Rabban Hormizd monks.

[26] On 13 October 1837, conscious that he had not long to live, Yohannan 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.