Arrillaga served as captain in the Spanish army in northern Mexico and Texas in the 1780s and 1790s. He was the comandante at Loreto, Baja California Sur.
In the context of his military career, Arrillaga played a role as a captain in the Spanish army's efforts to maintain control in northern Mexico and Texas from the late 1780s to the early 1790s. He was stationed at Loreto, Baja California Sur.