Family and upbringing
María de las Mercedes in 1874
She was born at the Palacio Real in Madrid, the sixth of her parents' nine children, none of whom died in infancy but only four of whom would live to the age of 20. Her mother's elder sister, Queen Isabella II, and brother-in-law, King Francis, served as Mercedes' godparents at her christening, when she was given the names: María de las Mercedes Isabel Francisca de Asís Antonia Luisa Fernanda Felipa Amalia Cristina Francisca de Paula Ramona Rita Cayetana Manuela Juana Josefa Joaquina Ana Rafaela Filomena Teresa Santísima Trinidad Gaspara Melchora Baltasara et omni sancti.
Although Mercedes was patrilineally a French princess, she was also a Spanish infanta and spent the first eight years of her life in Spain. Her childhood was spent at the palace of San Telmo in Andalusia, her father's rumoured aspirations to obtain his sister-in-law's crown periodically rendering him unwelcome at the royal court in Madrid.