On 12 October 1776 he sailed with an army from Cadiz, and spent the Southern Hemisphere summer in Buenos Aires, where he had been appointed Viceroy.

He then marched to Colonia del Sacramento, a disputed Portuguese city in present-day Uruguay, which surrendered almost immediately.

He then marched towards Rio Grande do Sul in Brazil, conquered Santa Catarina island, but received word from a treaty having been signed between Spain and Portugal and turned back.

He died on 26 December 1778 in the Capuchin Convent of Córdoba (Spain), where he was staying on his way to the Spanish Court.

He was buried in the Cordoba Cathedral in a sumptuous ceremony, a memorable event in the city's history.