Maria Klementyna Sobieska was a Polish princess, the daughter of Crown Prince Jakub Ludwik Sobieski and Hedwig Elisabeth Amelia of Neuburg.
She married Prince James Francis Edward Stuart in the Cathedral of Santa Margherita, Montefiascone, Italy, on 3 September 1719.
They lived in Rome at the request of Pope Clement XI, who acknowledged them as the Catholic King and Queen of England, Scotland and Ireland. The Catholic Church also provided them with an annual allowance from the Papal treasury.
The marriage produced two sons, "Bonnie Prince Charlie" Charles Edward Stuart and Cardinal Henry Benedict Stuart.
Maria died at the age of 32 in Rome, interred with full royal honors in St. Peter's Basilica. Pope Benedict XIV commissioned a monument to her memory that resides in the Basilica (findagrave.com)