Maximilian Joseph Eugene Auguste Napoleon de Beauharnais, 3rd Duke of Leuchtenberg (2 October 1817 Munich – 1 November 1852 St.Petersburg), 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. He was a grandson of Napoleon I's first wife, the Empress Josephine, by her prior marriage to Alexandre de Beauharnais.

Childhood

He was born as the second son of Eugène de Beauharnais and Princess Augusta Amalia Ludovika Georgia of Bavaria. His maternal grandparents were Maximilian I, King of Bavaria and his first wife Marie Wilhelmine Auguste, Landgravine of Hesse-Darmstadt.

His maternal grandmother Marie Wilhelmine Auguste was a daughter of Georg Wilhelm of Hesse-Darmstadt, younger son of Louis VIII, Landgrave of Hesse-Darmstadt.

He was a brother of:

• Auguste de Beauharnais, Duke of Santa Cruz, Consort prince of Queen Maria II of Portugal;
• Amélie de Beauharnais, Empress consort of Pedro I of Brazil;
• Josephine of Leuchtenberg, queen consort of Oscar I of Sweden.

Duke of Leuchtenberg

His maternal grandfather Maximilian of Bavaria appointed Eugène de Beauharnais, 1st Duke of Leuchtenberg on 14 November 1817. The title came with the effective administration of the Principality of Eichstätt. Maximilian was named "Prince of Leuchtenburg" and became the second-in-line heir to the Duchy.

On 21 February 1824, his father died and his older brother became Auguste de Beauharnais, Duke of Leuchtenberg. His brother was yet childless and Maximilian became his Heir Presumptive.

Auguste eventually married Queen Maria II of Portugal but died childless on 28 March 1835. Maximilian became the 3rd Duke of Leuchtenberg at this point.

Marriage

He married Grand Duchess Maria Nikolayevna of Russia on July 2, 1839 in the chapel of the Winter Palace. She was the eldest daughter of Nicholas I of Russia and Charlotte of Prussia.

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. His father was an adoptive son of Napoleon.

Children

1. Princess Alexandra Maximilianovna (1840–1843) died in childhood
2. Princess Maria Maximilianovna (1841–1914) m. Prince Wilhelm of Baden (1829–1897), younger son of Leopold, Grand Duke of Baden
3. Nicholas Maximilianovich, Duke of Leuchtenberg (1843–1891) m. Nadezhda Annenkova (1840-1891)
4. Princess Eugenia Maximilianovna (1845–1925) m. Duke Alexander Petrovich of Oldenburg (1844–1932)
5. Eugen Maximilianovich, Duke of Leuchtenberg (1847–1901) m. Daria Opotchinina (1845–1870) m. Zinaida Skobeleva (1856–1899)
6. Prince Sergei Maximilianovich (1849–1877) Killed in the Russo-Turkish war
7. Georgi Maximilianovich, Duke of Leuchtenberg (1852–1912) m.(1) Duchess Therese Petrovna of Oldenburg (1852–1883) m.(2) Anastasia of Montenegro (1868–1935)

Further descendants

Through his oldest surviving daughter Princess Maria Maximilianovna of Leuchtenberg (1841–1914), he is the grandfather of Prince Maximilian of Baden (1867–1929), Chancellor of Germany during World War I.

His youngest daughter Princess Eugenia Maximilianovna of Leuchtenberg (1845–1925) married Duke Alexander Petrovich of Oldenburg (1844–1932), the grandson of Grand Duchess Catherine Pavlovna of Russia, and became the mother of Duke Peter Alexandrovich of Oldenburg (1868–1924), the divorced husband of Grand Duchess Olga Alexandrovna of Russia (1882–1960), the youngest sister of Nicholas II of Russia.