A lieutenant general of cavalry, Portocarrero y Lasso de la Vega distinguished himself on campaign with John of Austria the Younger in Sicily, Flanders, Catalonia and Portugal. He was in the Battle of Arras, Condé and Saint Guillaume. He lost his right arm in the Battle of the Dunes at Dunkirk in June 1658. He had a prosthesis made of silver, and his soldiers nicknamed him "Brazo de Plata" (Arm of Silver).