Duke Alexander Petrovich of Oldenburg

Duke Alexander Petrovich of Oldenburg was the second son of Duke Peter Georgievich of Oldenburg and his wife Princess Therese of NassauWeilburg. Though he had a German title and ancestry, Alexander and his siblings were born and raised in St. Petersburg as the grandchildren of Grand Duchess Catherine Pavlovna of Russia.

OnJanuary 1868, Alexander married Princess Eugenia Maximilianovna of Leuchtenberg, a daughter of Maximilian de Beauharnais, 3rd Duke of Leuchtenberg. Like his own family, Eugenia was also an offshoot of the Imperial family, as her mother was Grand Duchess Maria Nikolaevna, eldest daughter of Nicholas I of Russia. She was entitled to the rank Imperial Highness, and was born and raised in St. Petersburg.

Source: Wikipedia