Anza is the leader of this expedition and the author of this diary. He was the commander of the presido at Tubac and earlier had found the route from Tubac to Alta California. Later in life he was the governor of New Mexico, where in 1779 he defeated the Comanches in battles in what is now the state of Colorado. Anza was born at the presidio of Fronteras in 1736 and died in Arizpe in 1789.

The word "Don" in his name stands for "de origen noble" in Spanish and means "of noble origin" in English. Thus, signifying nobility, it is placed as a title in front of a person's name, like "Mr." or "Sir." The equivalent title for women is "Doña."