Refusing previously the patriarchal position for two times, this time he accepted it because of Rome pressure.
The years of pursuits gave a negative result and the patriarchate of Gregory VIII knew a period of revival, prosperity and organization. During his patriarchate, due to the religious freedom, he established new eparchies, constructed 15 churches, many chapels, built priests' houses and schools, he even established a seminary to increase the education level, he corrected the book of regulations, he published booklets, he translated and enriched the convent library.

Talking about this Armenian clergyman, Emir Bachir II was saying:
In 1855, he assembled the first national Synod of Armenian Catholic patriarchate in Bzommar , during which he made clerical, canonical, administrative , pastoral and ritual reforms.
He made friendly relations with the country clerical and political dictators. The friendship with the Daoud Artine Pasha was known. "Your friend" died, wrote to him when Emir Bachir II died in Constantinople.
The eight Lebanese patriarchs, accomplished their missions in the most difficult conditions without an official recognition for 150 years, under prison and death menace. The unanimous preachers, disguising as a miller , a camel-driver or a peddler, wandered from house to another , tricked the police and they evangelized their people. If they were free for 150 years they could realize many things.
The witness of their activity is the French De Damas who wrote these lines in 1888. "In ten years, the preachers of Bzommar spreaded the kingdom of God in Syria, and Minor Asia. They showed what can do a well prepared clergyman. The name of the last catholicos of Bzommar is going to remain glorious in the annals of his nation".
With Gregory VIII, the range of the Lebanese patriarchs ended and the Seat was transferred to Constantinople.