The Archduke Charles rallying his troops at the Battle of Aspern Austrian archduke, field marshal, army reformer, and military theoretician who was one of the few Allied commanders capable of defeating the French generals of the Napoleonic period. He modernized the Austrian army during the first decade of the 19th century, making it a formidable fighting force that contributed materially to Napoleon's defeat in 1813-15. Archduke Charles gained important successes for the Austrian army at Aspern and Essling (May 21-22, 1809), an indication that the strategic mastery of the French was drawing to a close. 固opFoto