Eugène de Beauharnais Eugène Rose de Beauharnais ( 3 September 1781 – 21 February 1824 ) , was the first child and only son of Alexandre de Beauharnais and Joséphine Tascher de la Pagerie , future wife of Napoleon I . He was born in Paris , France and became the stepson and adopted child ( but not the heir to the imperial throne ) of Napoleon I . His biological father was executed during the revolutionary Reign of Terror . He commanded the Army of Italy and was Viceroy of Italy under his stepfather . Historians have looked upon him as one of the ablest of Napoleon ' s relatives . Military career . Eugène ' s first campaign was in the Vendée , where he fought at Quiberon . However , within a year his mother Joséphine had arranged his return to Paris . In the Italian campaigns of 1796 – 1797 , Eugène served as aide - de - camp to his stepfather , whom he also accompanied to Egypt . In Egypt , Eugène was wounded during the Siege of Acre ( 1799 ) . He returned to France in the autumn of 1799 and helped bring about the reconciliation between Bonaparte and his mother , who had become estranged due to the extramarital affairs of both . When Napoleon became First Consul , Eugène became a captain in the " Chasseurs à Cheval " of the Consular Guard . With his squadron he took part in the Battle of Marengo . During the War of the Fifth Coalition , Eugène was put in command of the Army of Italy , with General Étienne - Jacques - Joseph - Alexandre MacDonald as his military advisor . In April 1809 he fought and lost the Battle of Sacile against the Austrian army of the Archduke John , but Eugène ' s troops decisively won the rematch at the Battle of Raab that June . After the Battle of Aspern - Essling , Napoleon recalled the Army of Italy to Austria . After joining the main army on the island of Lobau in the Danube , Eugène took part in the Battle of Wagram . During the Russian campaign , Eugène again commanded the Army of Italy ( IV Corps ) with which he fought in the Battle of Borodino and the Battle of Maloyaroslavets . After Napoleon and then Joachim Murat had left the retreating army , Eugène took command of the remnants and led it back to Germany in 1813 . During the campaign of 1813 , Eugène fought in the Battle of Lützen . Napoleon then sent him back to Italy , where he organised the defence against the Austrians , holding out on the Mincio until the abdication in 1814 . After the fall of Napoleon in 1814 , Eugène retired to Munich and at the behest of his father - in - law King Maximilian of Bavaria , did not get involved with Napoleon and France again . Status and titles . In 14 June 1804 he was made an official member of the imperial family as His Imperial Highness , French Prince ( " Prince français " ) Eugène de Beauharnais . By a statute of 5 June 1805 the Emperor added " Viceroy of Italy " to his titles . Prince Eugène was adopted by Napoleon on 12 January 1806 , though excluded from succession to the French Empire . On 16 February 1806 , Eugent was declared heir presumptive to the Kingdom of Italy , in the absence of a second son of Napoleo . On 20 December 1807 he was given the title of " Prince de Venise " ( " Prince of Venice " ) , a title created on 30 March 1806 , when the Venetian Province taken from Austria in 1805 was united to Bonaparte ' s Kingdom of Italy . In 1810 , his stepfather also made him heir to the Grand Duchy of Frankfurt , held by Karl von Dalberg , Archbishop of Regensburg . Hence when the Archbishop abdicated as Duke in 1813 , Eugene technically succeeded . This position , however , was purely theoretical , as the abdication was due to the Grand Duchy ' s imminent conquest by the Allied armies . A further imperial sinecure was " Archichancelier d ' Etat de l ' Empire de France " ( " Archchancellor of State of the Empire of France " ) . He was an active Freemason and was involved in setting up the Grand Orient of Italy and its Supreme Council . Family . On 14 January 1806 , two days after his adoption by Napoleon , Eugène married Princess Augusta Amalia Ludovika Georgia of Bavaria ( 1788 – 1851 ) , eldest daughter of Napoleon ' s ally , King Maximilian I Joseph of Bavaria . On 14 November 1817 , his father - in - law made him Duke of Leuchtenberg and Prince of Eichstätt . Eugène and Augusta had seven children : Eugène de Beauharnais died on 21 February 1824 in Munich . A biography by Carola Oman , " Napoleon ' s viceroy , Eugène de Beauharnais " , appeared in 1966 .