Maximilian Joseph Eugene Auguste Napoleon de Beauharnais, 3rd Duke of Leuchtenberg, Prince Romanowsky (2 October 1817 – 1 November 1852) was the husband of Grand Duchess Maria Nikolayevna of Russia and first cousin of Emperors Napoleon III of the French and Francis Joseph I of Austria.

A student of Moritz von Jacobi, he is known as one of pioneers in galvanoplasty and an expert in copper and bronze metalworks generally, as well as an art collector.

He was born as the second son of Eugène de Beauharnais, Duke of Leuchtenberg and Prince of Eichstätt and Princess Augusta Amalia Ludovika Georgia of Bavaria.

After the fall of the First French Empire and the restoration of the Bourbons in Paris in 1814, Maximilian's father fled France and found refuge with his wife's family in Munich.

[1] Victims of Bavarian protocols, which constantly reminded them that they were inferior to the Wittelsbachs, the Beauharnais family still benefited materially from their exile.

With his fortune, Prince Eugène acquired several castles and estates, including the Leuchtenberg Palace in Munich and land situated in the Canton of Thurgau in Switzerland.

His siblings made great marriages: Josephine to the future king of Sweden and Norway (1823), Eugenie to the Prince of Hohenzollern-Hechingen (1826), Amelie to the Emperor of Brazil (1829), Auguste to the Queen of Portugal (1834), and Theodelinde to the Duke of Urach (1841).

[1] His maternal grandfather Maximilian of Bavaria appointed his father, Eugène de Beauharnais, 1st Duke of Leuchtenberg on 14 November 1817.

Shortly after this, Tsar Nicholas I invited King Ludwig I of Bavaria to send a prince of his house to attend military maneuvers in Russia.

After having consulted his mother, Maximilian accepted the tsar's conditions, and his engagement to Maria was officially announced on 5 December, 1838.

15 days of festivities followed,[2] but Muscovites disapproved, shocked to see one of their princesses married to a French prince whose father had participated in taking their city in 1812.

His father-in-law Nicholas I granted to him on 14 July 1839 the Russian and Finnish style Imperial Highness, a rank he was entitled to as a descendant of the extended dynasty of Napoleon I of France.

Most historians believe that Maximilian was not the real father of the princes Eugene, Serge, and George of Leuchtenberg, who were in reality the sons of Stroganov.

Passionate about art and science, the prince augmented the collections of paintings, minerals, and arms he had inherited from his father and brother.

[1] The prince died on 1 November, 1852 in St. Petersburg, and his father-in-law declared a mourning period of three months, just like for any member of the imperial house.