Spanish princess, daughter of Queen Isabella II of Spain. She was the seventh of ten children of Francisco de Asís de Borbón. Aged seven years she accompanied her mother into exile in France. In Paris, she was educated at the College of the Sacred Heart. One year after the fall of Napoleon III, the Infanta, with the rest of the royal family, settled in Geneva. In 1873 she received her first communion in Rome at the hand of Pope Pius IX.
Two years later she returned to Spain once the monarchy was restored to her brother, King Alfonso XII, and has since lived on in Seville and Madrid. In July 1879 she went with her siblings, Isabel, Alfonso Maria de la Paz, and Eulalia to spend a few days in the resort of Escoriaza, in the province of Guipuzcoa. There, on August 3, while in bed to rest from the trip, she suffered an acute attack of convulsions and lockjaw, and eventually lost consciousness. Two days later she died, probably of tuberculous meningitis. However, the official medical report diagnosed a serous effusion. She was buried a few days later in El Escorial.
Although not married, Maria del Pilar was in love with the son of Napoleon III, Napoleon Louis. The Empress Eugenia de Montijo and Queen Isabella II were in favor of this bond, but the young Prince Napoleon met his death in the war against the Zulus two months before the death of the princess herself.
Years later, her sister, the Infanta Maria de la Paz, married Prince Louis Ferdinand of Bavaria and decided to call her only child María del Pilar, in memory of her sister. Thus, she introduced a Spanish name into the house of Wittelsbach.

Link to Wikipedia (Spanish)