Upon taking over the archdiocese of Guatemala, began preparing to travel all across his new dominion; he sent letter to all the secular priests ahead of time so they were ready to have a report for him upon his arrival.

[4] On 12 June 1773 Capitain General Martín de Mayorga was inaugurated, and alongside Cortés y Larráz and the regular clergy vicars, were the top authorities in the Kingdom of Guatemala and would be the main characters in the events that followed the 1773 earthquakes.

Permission was granted on 2 January 1776, and the new location chosen is where the modern Guatemala City sits, by then led by Captain General Matías de Gálvez y Gallardo.

On the other hand, Cortés y Larraz opposed the move, as he realized that it would represent a loss of both power and revenue for his archdiocese; besides the convents and temples needed to be built again, and he did not have enough money to support that.

He brought along a large group for support which was carefully chosen as they had a well defined political goal: take control of the Guatemalan secular clergy, which was in almost open rebellion.