From there he went to Peru, when Viceroy José Fernando de Abascal y Sousa named him directory of the Royal Artillery.

After these victories he advanced to the south, occupying the cities of Jujuy (northern Argentina) on May 27, 1814, and Salta on July 25, 1814.

However, he was forced to withdraw under continuing harassment by General Martín Miguel de Güemes's gauchos.

By royal order dated October 15, 1815, he was named interim viceroy of Peru to replace Abascal.

Permission was received in May 1819, and in September, de la Serna resigned the command of the army to General José Canterac.

De la Serna, through secret negotiations, was named commander-in-chief of the army gathered at Aznapuquio to protect the capital against San Martin's advance.

His nephew was Manuel de la Pezuela y Lobo-Cabrilla, a conservative politician, who was minister of the navy and of commerce in the Spanish cabinet, and later a senator.

As a result, naval officer Fernando Villaamil conceived the ocean going torpedo gunboat Destructor, built in 1885 in Britain and a precursor of the modern destroyers.