Prince Louis Léopold Charles Marie André Poniatowski (24 January 1864 – 8 March 1954), was a Polish nobleman, member of the House of Poniatowski who became a prominent French financier and industrialist. Early life Prince Poniatowski was born in Paris, France on 24 January 1864. He was the youngest son of Prince Stanisław August Poniatowski (1835–1908) and Countess Louise Le Hon (1838–1931). His father served as Master of Horse to Emperor Napoleon III of France. He had an older sister and brother, Prince Charles Poniatowski, who married Maud Ely Goddard of New Brighton (a grand-niece of Mayor Smith Ely Jr.). His maternal grandparents were Charles de Morny, Duke of Morny and the Countess Le Hon ( Fanny Mosselman; although she was married to Count Charles Le Hon when Louise was born). His paternal grandparents were Prince Józef Michał Poniatowski, a prominent composer and a singer, and Countess Matilda Perotti. Prince Poniatowski graduated from the French Saumur School of Cavalry. Career In pursuit of investment opportunities, Poniatowski went to San Francisco and formed a syndicate to rework old Gold Country mines using modern methods. To facilitate transportation, he backed Thomas S. Bullock in the construction of the Sierra Railway to get to the mines, and financed construction of the Blue Lakes powerhouse on the Mokelumne River to get electric power to the mines. Realizing the vast potential of this river for hydroelectric power, Poniatowski and his brother-in-law, William Henry Crocker, he formed the Standard Electric Co. in 1897 to build Electra Powerhouse (which later merged into the Pacific Gas and Electric Company). In addition to their railway, mining and power interests, Poniatowski and Crocker built Tanforan Racetrack near Sky Farm, his winter residence in Burlingame. Return to France In 1904, after fifteen years in California, he sold his interests and returned to France with his family. He became "one of the leading authorities on finance, headed the French Finance Company, formed to float issues of American securities in France, and was head of Banque Privée." In World War I, at the age of 52, he served in the French Army as liaison officer with the British Army. Personal life On 6 October 1894, Poniatowski married Elizabeth Helen Sperry (1872–1911), an heiress from Stockton, California, in Paris. A daughter of Simon Willard Sperry and Caroline Elizabeth ( Barker) Sperry, her sister, Ethel (née Sperry) Crocker, was the wife of banker William H.