When Antonio Maria Bucareli took up his duties in 1771 as the forty-sixth viceroy of New Spain, he assumed command of a magnificent complexity of land areas, large and small, whose people constituted a cultural and social entity ranging from the traditional Apache to the European gentleman of the Enlightenment.

He governed a key area at a significant time. Shortly before Bucareli's arrival in Mexico, Jose de Galvez had completed an intensive inspection of the country, had instituted many reforms, and was ready to present the new viceroy with progressive policies for administrative...