English-born, Scottish great-grandmother of Prince Rainier III of Monaco, the fashion designer Prince Egon von Fürstenberg, the socialite and actress Princess Ira von Fürstenberg and the Czech Minister of Foreign Affairs Prince Karel Schwarzenberg. She was the daughter of William Alexander Anthony Archibald Hamilton, 11th Duke of Hamilton and of his wife, Princess Marie Amelie Elizabeth Caroline of Baden. Through her maternal grandmother, she was a third cousin of Emperor Napoléon III of France. She was a first cousin of Queen Carola of Saxony, Queen Stephanie of Portugal, King Carol I of Romania, and Princess Marie, Countess of Flanders (mother of King Albert I of the Belgians).
Her first marriage, on 21 September 1869 at Château de Marchais, was to Prince Albert, only child and heir of Charles III, Prince of Monaco. Mary Victoria bore Prince Albert a single son, Louis, who would take the throne of Monaco upon his father’s death. Their marriage was annulled by the Church on 3 January 1880 (although civilly it was dissolved only on 28 July 1880 by the Order of Prince Charles III).
Her second marriage, on 2 June 1880, was to Count Tassilo Festetics de Tolna. The couple had four children. During her 40-year marriage to Graf, and later Prince Festetics, Lady Mary oversaw enlargement and improvement of the Festetics’ main seat, Festetics Palace, and its gardens, in Keszthely, western Hungary. On numerous occasions, she and her husband would entertain her brother the Duke of Hamilton, and his great friend, the Prince of Wales.
She died on 14 May 1922, aged 71, in Budapest, Kingdom of Hungary.
Link to Wikipedia biography