After returning to Spain, he was appointed as Viceroy of Navarre, Capitan General of Catalonia and, lastly, served Carlos III as his Secretary of War.
In July 1763, after Great Britain defeated France in the Seven Years' War, it also signed the Treaty of Paris with Spain, settling control of territories in North America.
France ceded its territories east of the Mississippi River to Britain, and West Louisiana (and Caribbean islands) to Spain.
During his short administration he improved defenses: repairing the fortifications of the city of Havana, and beginning construction of the great fortress known as La Cabaña.
In addition, he improved government administration, organizing the department of finances, the police, the militia, and the hospitals.