Ottavio Piccolomini, an Austrian general, born in 1599, died in Vienna in 1656. He was a descendant of a sister of Pope Pius II. He early entered the Spanish army at Milan, served under the emperor Ferdinand II. against the Bohemians, and is said to have commanded at the battle of Lutzen the cavalry regiment in an encounter with which Gustavus Adolphus lost his life (1632). He was subsequently appointed to a high military command by Wal-lenstein, but when that general meditated treason he informed the emperor of the plot, and was ordered by Ferdinand to capture Wallenstein dead or alive. Before he could execute this command the latter was assassinated (1634), and Piccolomini received part of the Wallenstein estate. During the remainder of the thirty years' war he held important commands against the Swedes. In 1635 he drove the French from the Netherlands, but was less successful against the Dutch. His victories over the Swedes led Philip IV. of Spain to ask his services, and he fought a second time with advantage at the head of the Spanish forces against the French and Dutch. In 1648 he was recalled and made marshal.

After the peace of Westphalia he was sent to the convention of Nuremberg (1649), with full powers, and subsequently was made a prince of the empire, the king of Spain having reinstated him in his hereditary fief of the duchy of Amalfi. He was childless, and his son Max, in Schiller's "Wallenstein," is a fiction.