He also served, briefly, as interim governor of Texas in 1815, replacing Cristóbal Domínguez, as did his predecessor Benito Armiñán, although he only governed for a week or one year (according to different authors).
In May 1807, after the arrival of Zebulon M. Pike's troops to Guajoquilla, Valera accompanied them to the Presidio of Río Grande, located in the catholic mission San Juan Bautista, Coahuila.
In June of the following year, Varela was assistant to the new Commanding officer of Texas, the Peninsular Spanish Bernardo Bonavía y Zapata.
In this capacity he took part in the Bonavía meetings, which were held to discuss certain economic reforms the commander proposed implementing.
For a time, Varela commanded the Texas Cavalry, but on July 20, 1815[1] he was appointed interim governor of the North American province.