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Archduke Charles of Austria, Duke of Teschen (German: Erzherzog Carl Ludwig Johann Joseph Laurentius von Osterreich, Herzog von Teschen; 5 September 1771 - 30 April 1847) was an Austrian field-marshal, the third son of Emperor Leopold II and his wife, Maria Luisa of Spain. He was also the younger brother of Francis II, Holy Roman Emperor. Despite being epileptic, Charles achieved respect both as a commander and as a reformer of the Austrian army.

In 1797 he was sent to arrest the victorious march of General Bonaparte in Italy, and he conducted the retreat of the over-matched Austrians with the highest skill. In the campaign of 1799 he once more opposed Jourdan, whom he defeated in the battles of Ostrach and Stockach, following up his success by invading Switzerland and defeating Massena in the First Battle of Zurich, after which he re-entered Germany and drove the French once more over the Rhine.  Ill-health, however, forced him to retire to Bohemia, but he was soon recalled to undertake the task of checking Moreau's advance on Vienna. The result of the Battle of Hohenlinden had, however, foredoomed the attempt, and the archduke had to make the armistice of Steyr. His popularity was now such that the Perpetual Diet of Regensburg, which met in 1802, resolved to erect a statue in his honor and to give him the title of savior of his country, but Charles refused both distinctions.  In the short and disastrous war of 1805 Archduke Charles commanded what was intended to be the main army in Italy, but events made Germany the decisive theatre of operations; Austria sustained defeat on the Danube, and the archduke was defeated by Massena in the Battle of Caldiero. With the conclusion of peace he began his active work of army reorganization, which was first tested on the field in 1809.  In 1806 Francis II (now Francis I of Austria) named the Archduke Charles, already a field marshal, as Commander in Chief of the Austrian army and Head of the Council of War. Supported by the prestige of being the only general who had proved capable of defeating the French, he promptly initiated a far-reaching scheme of reform, which replaced the obsolete methods of the 18th century. The chief characteristics of the new order were the adoption of the nation in arms principle and the adoption of French war organization and tactics. The army reforms were not yet completed by the war of 1809, in which Charles acted as commander in chief, yet even so it proved a far more formidable opponent than the old and was only defeated after a desperate struggle involving Austrian victories and large loss of life on both sides.  Its initial successes were neutralized by the reverses of Abensberg, Landshut and Eckmuhl but, after the evacuation of Vienna, the archduke won a strong victory at the Battle of Aspern-Essling but soon afterwards lost at the Battle of Wagram. At the end of the campaign the archduke gave up all his military offices.
Archduke Charles, Duke of Teschen