Following these illustrious rewards, Piccolomini had expected to be appointed as successor to Matthias Gallas. Instead of being appointed, though, he was called in to act as an assistant to Archduke Leopold Wilhelm of Austria, with whom he served in the second battle of Breitenfeld in 1642. Thereafter he spent several years in the Spanish service and received the title of grandee and induction into the Order of the Golden Fleece.