Argüelles Sr. was the first Alcalde (Mayor) of San Agustín, and had been in charge of munitions in the Florida forts of Santa María, San Agustín (now St. Augustine), and Santa Elena.
Argüelles Sr.'s role as the first mayor of San Agustín involved overseeing military supplies at the forts of Santa María, San Agustín (now St. Augustine), and Santa Elena.