In 1634, the castle and estate passed into the hands of Italian nobleman Ottavio Piccolomini de Arragona as a reward for his help in removing Wallenstein. Ottavio, then 35 years old, had already served a long military career, during which he gained extensive experience in warfare. He joined the army at the age of 17, took part in the Battle of White Mountain, and later became commander of Wallenstein's personal guard. In the Battle of Lützen, Ottavio's "black riders" killed the Swedish king Gustav II Adolf. His military successes were accompanied by social advancement, and Ottavio was first promoted to the rank of count for his services. For defeating the French army near the town of Thionville in 1639, he was rewarded by King Philip IV of Spain with the Duchy of Amalfi, and in 1643 he received the Order of the Golden Fleece. Towards the end of the war, he commanded the imperial troops in Bohemia. Finally, after diplomatic negotiations on the terms of the Peace of Westphalia, in which he participated as the imperial plenipotentiary, he crowned his successful career by acquiring the hereditary title of Imperial Prince. He was also a holder of the Order of Saint Stephen. The Piccolomini family owned the estate until 1783, and during their reign, the castle took on its present form.