During the Second World War, Karl Ludwig and his brother Felix volunteered to serve in the 101st Infantry Battalion of the United States Army, known as the "Free Austria Battalion". However, the battalion was disbanded when a number of exiled Jewish volunteers who made up the majority of the force ultimately declined to confirm their enlistment.
Archduke Rudolf of Austria, son of Carl Ludwig, during a presentation about grandmother Zita in Brno (2014)
Archduke Rudolf of Austria (born 1950); married Baroness Hélène de Villenfagnede Vogelsanck (b. 1954) in Brussels 3 July 1976, their family taking up residence in Belgium thereafter. On 29 May 1978 he, his children and male-line descendants were incorporated in the nobility of Belgium by royal letters patent with the hereditary title Prince/sse de Habsbourg-Lorraine and the style of Serene Highness. Rudolf works at investment managers AAA Gestion, based in Villars-sur-Glâne, Switzerland. He and Hélène have eight children:
Archduke Carl Christian of Austria (b. 1977); married on 2 June 2007 Estelle de Saint-Romain (b. 1979):
Archduchess Zita of Austria (b. 2008).
Archduchess Anezka of Austria (b. 2010).
Archduchess Anna of Austria (b. 2012).
Archduchess Paola of Austria (b. 2014).
Archduchess Priscilla of Austria (b. 1979).
Archduke Johannes of Austria (b. 1981).
Archduke Thomas of Austria (b. 1983).
Archduchess Marie-des-Neiges of Austria (b. 1986).
Archduke Franz-Ludwig of Austria (b. 1988); married on 1 September 2018 Mathilde Vignon (b. 1992).
Archduke Michael of Austria (b. 1990).
Archduke Joseph of Austria (b. 1991).
Archduchess Alexandra of Austria (born 1952); married Chilean ambassador to the Holy See Héctor Riesle. Three children:
Felipe Riesle (b. 1986), married to Pilar Huidoboro:
Archduke Christoph of Austria (b. 1988); married to Adélaïde Drapé-Frisch (b. 1989) on 28 December (civil) and 29 December 2012 (religious) in Nancy, France.
Archduchess Katarina of Austria (b. 2014).
Archduchess Sophia of Austria (b. 2017).
Archduke Alexander of Austria (b. 1990).
Archduchess Gabriella of Austria (b. 1994)
Victoria (b. 2017)
Archduchess Maria Constanza of Austria (born 1957); married Franz Josef, Prince (Fürst) von Auersperg-Trautson. Three biological daughters (one died shortly after her birth) and one adopted daughter, Anna Maria:
Princess Alexandra Maria (1998–1998).
Princess Ladislaya (b. 1999).
Princess Eleonora (b. 2002).
Ancestors of Archduke Carl Ludwig of Austria (1918–2007)