DukeJulius Siegmund of Württemberg-Juliusburg (18 August 1653 inOleśnica – 15 October 1684 inDobroszyce) wasDuke ofWürttemberg-Juliusburg.

Julius Siegmund was the fourth son of the DukeSilvius I Nimrod of Württemberg-Oels (1622–1664) from his marriage toElisabeth Marie, Duchess of Oels (1625–1686) .

After his father's death in 1664, his mother initially ruled theDuchy of Oels as regent for her four sons. The sons went on theirGrand Tour and visited, among other countries, the Netherlands, where the eldest brother Charles Ferdinand died in 1669.

In 1672, the elder brothers took up government and divided the country. Julius Siegmund, who was still under the regency of his mother, receivedMiędzybórz. His older brotherSilvius II Frederick received Oels andChristian Ulrich I receivedBernstadt.

In 1673, Elisabeth Marie stepped down as regent and Julius Siegmund began to rule himself. He chose the village of Dreske as his residence. He expanded the castle in the village to abaroque residence. He name the castle and the villageJuliusburg, after himself.

Julius Siegmund was a member of theFruitbearing Society, under the nicknameder Unverwelkte ("the unwithered one").

Julius Siegmund married on 4 April 1677 inGrabow with Anna Sophia (1647–1726), the daughter of theAdolf Frederick I of Mecklenburg-Schwerin. They had the following children:

• Marie Sophie (1678–1681)
• Leopold Frederick (1680–1681)
• Charles (1682–1745), Duke of Württemberg-Bernstadt

married in 1703 with Princess Wilhelmine Louise of Saxe-Meiningen (1686-1753)

• Friedrich Schiller:Geschichte von Württemberg bis zum Jahr 1740, p. 229
• Michael Morgenbesser and Karl Adolf Menzel:Geschichte Schlesiens, p. 284 ff

• Marek, Miroslav."Genealogy of Württemberg". Genealogy.EU.