Even as an officer in the royal navy, Martino began to study art at the academy of his native city of Naples. On a voyage to South America with his fleet, he quit the service in 1868 in order to devote himself entirely to painting — with great success, as demonstrated by his appointment as court painter to the last Brazilian emperor, Pedro II.
After his return in 1875, the high aristocracy of Europe would number among Martino’s clients, until Queen Victoria engaged him exclusively in 1894 as her court’s marine painter.