Mariano Téllez-Girón, 12th Duke of Osuna

Mariano Téllez-Girón y Beaufort Spontin, 12th Duke of Osuna, GE, OM, LH, OAN, KA (19 July 1814 – 2 June 1882), was a Spanish peer, diplomat and army officer, whose lavish exploits as Ambassador of Spain to the Russian Empire earned him admiration and popularity amongst European courts. He was a younger brother of Pedro de Alcántara Téllez-Girón, from whom he inherited his 59 peerage titles when he died prematurely in 1844.[1]

The Most Excellent The Duke of Osuna GE OM LH OAN KA
Portrait by Valentín Carderera, c. 1833
Personal details
Born	Mariano Francisco de Borja José Justo Téllez-Girón y Beaufort Spontin 19 July 1814 Madrid, Spain
Died	June 2, 1882(1882-06-02) (aged 67) Beauraing, Belgium
Parents	Francisco de Borja Téllez-Girón, 10th Duke of Osuna (father) María Francisca Beaufort Spontin y Álvarez de Toledo (mother)
Signature

Born to one of the most influential families in the Kingdom of Spain, he quickly followed the steps of his father into the military, and was made a cadet age 19. The Duke of Osuna, at the time styled Marquess of Terranova, saw action in many fronts of the First Carlist War, being profusely decorated in July 1836.[2] From 1838, he was member of parliament for Cádiz and worked as a military attaché in different embassies.

In 1856, Osuna was sent to Saint Petersburg as ambassador by Queen Isabella II, who despite her low regard for him, was aware of his likeable character. The duke, "a formidable dandy",[3][4][5][6] was ultimately sent to recover the prestige of a decadent Spain in the complex Tsar court, influenced at the time by the English and French envoys.[7] During his tenure as ambassador in Saint Petersburg, he achieved the resumption of strong diplomatic relations between the Kingdom of Spain and the Russian Empire, broken at the death of Ferdinand VII. The sumptuous parties he gave at the Spanish embassy paid for out of his own pocket became world famous. As claimed by Valera and Béthencourt, in one occasion, the Duke of Osuna celebrated an opulent dinner in which he ordered that the guests threw the entirety of the tableware of gold through the windows of his palace and into the River Neva, so as to spare washing effort to his servants.[8][9] In fact, his wealth was so extraordinary, that it was alleged that he could travel from Santander to Cádiz without leaving his possessions at all.[10]

Osuna died in 1882, childless and in financial ruin. According to an author, "the refined duke consumed himself in his own brilliance".[11] The seventeen million pesetas (plus assets) he had inherited after the death of his brother were brought down to liabilities of around forty million at his death.[12] The expression "not that you were Osuna" was coined after him, and is still widely used in reference to someone who displays flamboyant expenses and wealth.[13][14][15]