Lady Mary Victoria Douglas-Hamilton

Her first marriage, on 21 September 1869 at Château de Marchais, was to Prince Albert, only child and heir apparent of Charles III, Prince of Monaco. The marriage was arranged upon the wish of the Monegasque princely house, as it had long been an ambition of his mother and grandmother to marry him to a member of the British royal house.[2] While Queen Victoria refused a match between Albert and one of her closer family members, Lady Mary was suggested as a suitable replacement.[3]

They had 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. There are still portraits extant in the Palace of numerous members of her family, including one of her father in full Highland dress. Outside the palace, on either side of the main entrance there are the Armorial bearings of both the Lady Mary and her husband.

Further, the Helikon Library at the Palace contains many works that were brought to Keszthely by Lady Mary from her father and brother's collections at Hamilton Palace.

The Palace grounds, on the shores of Lake Balaton, contains a Mausoleum to the Festetics and is the final resting place of Lady Mary and her husband.