Archduke Karl Ludwig Joseph Maria of Austria (30 July 1833 – 19 May 1896) was the younger brother of Franz Joseph I of Austria (1830-1916), the father of Archduke Franz Ferdinand of Austria (1863-1914), whose assassination ignited World War I, and grandfather of the last emperor,  Charles I.
He was born at
Schönbrunn Palace in Vienna, the son of Archduke Franz Karl of Austria (1802-1878) and his wife Princess Sophie of Bavaria (1805-1872).
His mother ensured he was raised a devout Roman Catholic by the Vienna Prince-archbishop
Joseph Othmar Rauscher, a conviction that evolved into religious mania in his later years.
Though not interested in politics, the 20-year-old joined the
Galician government of Count Agenor Romuald Go?uchowski and in 1855 accepted his appointment as Tyrolean stadtholder in Innsbruck, where he took his residence at Ambras Castle. However, he found his authority to exert power restricted by the Austrian cabinet of his cousin Archduke Rainer Ferdinand and Baron Alexander von Bach. He finally laid down the office upon the issue of the 1861 February Patent for a life as patron of the arts and sciences.
As the eldest surviving brother of the Emperor, Karl Ludwig, after the death of his nephew Crown Prince
Rudolf of Austria in 1889, became heir presumptive to the Austro-Hungarian Empire. A newspaper article appeared shortly after the death of his nephew claiming that the Archduke had renounced his succession rights in favor of his eldest son Franz Ferdinand. This rumor proved to be false.  
Marriage and family
Princess Margaretha of Saxony
Princess Maria Annunciata of Bourbon-Two Sicilies, Archduchess of Austria
Karl Ludwig and his third wife, Maria Teresa of Portugal
Karl Ludwig married three times.
His first wife, whom he married on 4 November 1856 at
Dresden, was his first cousin Margaretha of Saxony (1840-1858), the daughter of Johann of Saxony (1801-1873) and Amalie Auguste of Bavaria (1801-1877). She died on 15 September 1858 and they had no children.
His second wife, whom he married by proxy on 16 October 1862 at
Rome, and in person on 21 October 1862 at Venice, was Princess Maria Annunciata of Bourbon-Two Sicilies (1843-1871), daughter of Ferdinand II of the Two Sicilies (1810-1859) and Maria Theresa of Austria (1816-1867).
They had four children:
Maria Annunciata died on 4 May 1871.
His third wife, whom he married on 23 July 1873 at
Kleinheubach, was Infanta Maria Theresa of Portugal (1855-1944), daughter of Miguel I of Portugal (1802-1866) and Adelaide of Löwenstein-Wertheim-Rosenberg (1831-1909).
They had two daughters:
Karl Ludwig died of
typhoid at Schönbrunn in Vienna returning from a journey to Palestine and Egypt, allegedly after the consumption of contaminated Jordan waters. His widow, Maria Teresa died on 12 February 1944.
Honours Austrian decorations  Foreign decorations 
Baden: House Order of Fidelity, Grand Cross
Kingdom of Bavaria: Order of St. Hubert, Knight
Belgium: Royal Order of Leopold, Grand Cordon, 1853; wedding gift of King Leopold I in honour of his son and daughter-in-law. 
Empire of Brazil: Imperial Order of the Southern Cross, Grand Cross
Duchy of Brunswick: Order of Henry the Lion, Grand Cross
Denmark: Order of the Elephant, Knight, 21 July 1890 
Ernestine duchies: Saxe-Ernestine House Order, Grand Cross
Second French Empire: Legion of Honour, Grand Cross
Kingdom of Greece: Order of the Redeemer, Grand Cross
Grand Duchy of Hesse: Ludwig Order, Grand Cross
Kingdom of Italy: Order of the Annunciation, Knight
Second Mexican Empire: Imperial Order of the Mexican Eagle, Grand Cross
Nassau Ducal Family: Order of the Gold Lion of Nassau, Knight
Netherlands: Order of the Netherlands Lion, Grand Cross
Ottoman Empire: Order of Osmanieh, 1st Class with Diamonds
Kingdom of Portugal: Order of the Tower and Sword, Grand Cross 
Kingdom of Prussia:
Qajar dynasty: Portrait of the Shah of Persia with Diamonds
Kingdom of Romania: Order of the Star of Romania, Grand Cross
Saxe-Weimar-Eisenach: Order of the White Falcon, Grand Cross
Kingdom of Saxony: Order of the Rue Crown, Knight
Principality of Serbia: Order of the Cross of Takovo, Grand Cross
Siam: Order of the Crown of Siam, 1st Class with Diamonds
Spain: Order of Charles III, Grand Cross
Sweden-Norway: Royal Order of the Seraphim, Knight, 7 January 1870  Württemberg: Order of the Württemberg Crown, Grand Cross
Ancestors of Archduke Karl Ludwig of Austria
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"Austria's Insecurity" (PDF). The New York Times. 1896-06-16.
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Jørgen Pedersen (2009). (in Danish). Syddansk Universitetsforlag. p. 472. Riddere af Elefantordenen, 1559-2009 ISBN . 978-87-7674-434-2
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"Sveriges statskalender (1877) p.368" (in Swedish) . Retrieved – via runeberg.org.
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[ Genealogie ascendante jusqu'au quatrieme degre inclusivement de tous les Rois et Princes de maisons souveraines de l'Europe actuellement vivans Genealogy up to the fourth degree inclusive of all the Kings and Princes of sovereign houses of Europe currently living] (in French). Bourdeaux: Frederic Guillaume Birnstiel. 1768. p. 94.
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"Karoline Friederike Wilhelmine Königin von Bayern". Haus der Bayerischen Geschichte [House of Bavarian History] (in German). Bavarian Ministry of State for Wissenschaft and Kunst . Retrieved 2018.