Prince Louis Léopold Charles Marie André Poniatowski (24 January 1864 â 8 March 1954), was a Polish nobleman, member of the House of Poniatowski who became a prominent French financier and industrialist.
Prince André Poniatowski was born in Paris, France on 24 January 1864. He was the youngest son of Prince Stanisà Âaw August Poniatowski (1835âÂÂ1908) and Countess Louise Le Hon (1838âÂÂ1931). 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 Michaà  Poniatowski, a prominent composer and a singer, and Countess Matilda Perotti.
Prince Poniatowski graduated from the French Saumur Cavalry School.
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.
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.
During the Interwar and early World War II period, Poniatowski leaded the design of experimental infantry tank, SEAM G1P, which had reached the prototype stage, unlike the vehicles proposed by other contesters, however, without weapons and proper engine, which then was captured by German forces. He also proposed a design for superheavy tank, the SEAM 220t.
On 6 October 1894, Poniatowski married Elizabeth Helen Sperry (1872âÂÂ1911), an heiress from Stockton, California, in Paris. A daughter of Simon Willard Sperry and Caroline Elizabeth ( Barker) Sperry, her sister, Ethel Sperry Crocker, was the wife of banker William H. Crocker. Together, they were the parents of at least five sons, including:
In June 1911, the Princess attended the coronation of King George V in London with her sister. She died in Paris only two months later in August 1911, at only 39 years old. Poniatowski died on 8 March 1954 in Cahors, France.
Through his son Charles, he was a grandfather of French politician Michel Poniatowski (1922âÂÂ2002), who served as Minister of State and Minister of the Interior under his longtime friend, President Valéry Giscard d'Estaing (after having previously served as Minister of Health under President Georges Pompidou).
Through his youngest son Jean, he was a grandfather of writer Elena Poniatowska (b. 1932), who married Mexican astronomer Guillermo Haro.