On 25 October 1678, in
Wiener Neustadt, Johann Wilhelm married
Archduchess Maria Anna Josepha of Austria. She was a daughter of
Ferdinand III, Holy Roman Emperor, and his third wife,
Eleanor of Mantua. The wedding ceremony was performed by Archbishop
Leopold Karl von Kollonitsch. The couple settled in
Düsseldorf, where they led an elaborate royal household. During their marriage, Maria Anna Josepha gave birth to two children, but neither survived infancy: • A son (b. and d. Düsseldorf, 6 February 1683) • A son (b. and d. Vienna, 5 February 1686) Maria Anna Josepha died in 1689 of
tuberculosis. A couple of years later, on 29 April 1691, Johann Wilhelm
married by proxy Anna Maria Luisa de' Medici, daughter of
Cosimo III de' Medici, Grand Duke of Tuscany. She departed for Düsseldorf on 6 May 1691, accompanied by her younger brother,
Gian Gastone. Johann Wilhelm surprised her at
Innsbruck, where they officially married. Anna Maria Luisa became pregnant in 1692; however, she miscarried. Historians believed incorrectly that shortly after her arrival, she contracted
syphilis from her adulterous husband, which might have explained why Anna Maria Luisa and Johann Wilhelm failed to produce any children. In 2012, after concern caused by the
1966 Flood of the Arno River, the bones of Anna Maria Luisa were exhumed. A scientific examination found no traces of syphilis. == Art collections ==