In 1647, Maidalchini's counsin, Camillo Francesco Maria Pamphili, resigned his post as Cardinal-Nephew to marry and Innocent X required a new Cardinal Nephew. The pope destined for this task his sister-in-law's nephew, Francesco Maidalchini. Upon being elevated to Cardinal, he was installed as Cardinal-Deacon of Sant'Adriano al Foro.
Maidalchini was a creature of his aunt Olimpia Maidalchini. Instead of living in one of the many buildings of The Vatican, his aunt forced him to live at the Villa Pamphili with her. From there she directed his audiences with church leaders, often prodding him to provide answers she had provided him with in advance. He quickly proved so incompetent, however, that his appointment to the curial office of Cardinal-Nephew (officially styled as Superintendent of the Papal States) was never realised. His pitiful behaviour disgraced the Pope and in 1650, Maidalchini was replaced by Olimpia's cousin, and rival for political power, Camillo Astalli. Having blamed Olimpia for his disgrace, Francesco became her bitter enemy.
In 1653 Maidalchini was appointed Cardinal-Deacon of San Pancrazio. In 1654 he was appointed Cardinal-Deacon of the Church of Santa Maria in Portico and the following year, following the death of his "uncle", he participated in the papal conclave of 1655 which elected Pope Alexander VII. His aunt Olimpia died in 1657.
After only 8 years with Maidalchini as Cardinal-Deacon, the church of Santa Maria was in ruins and without income. Its deaconry was suppressed by Pope Alexander VII and the building was pulled down. Maidalchini was transferred (in title at least) to the newer Santa Maria in Campitelli, built by Carlo Rainaldi between 1659 and 1667.
Contemporary John Bargrave leaves little doubt that Maidalchini was not much respected either by the College of Cardinals or the general public of Rome. Bargrave describes Maidalchini as, "being within an inch of an idiot" and recounts that the ladies of one congregation could not help but laugh at the appearance of a teenager in cardinal's vestments. Maidalchini's could not contain himself and broke into laughter in response. Bargrave also recalled his run-in with a gentleman who kindly pointed out that the book the cardinal was reading was, in fact, upside down (Bargrave suggests Maidalchini was nearly illiterate).
Later ecclesiastic career
In 1666 Maidalchini was transferred to the deaconry of Santa Maria in Via Lata, which was customarily assigned to the senior Cardinal-Deacon, although it was only in 1669 when he assumed this position in the Sacred College. He participated in the conclave of 1667 which elected Pope Clement IX, the conclave of 1669-1670 which elected Pope Clement X, the conclave of 1676 which elected Pope Innocent XI and the conclave of 1689 which elected Pope Alexander VIII. As cardinal protodeacon, he announced the elections of the popes Clement X, Innocent XI and Alexander VIII and celebrated the rites of their coronations.
Later that year he was ordained as a priest and was appointed Cardinal-Priest of the Church of Santa Maria in Via. In accordance with the bull Postquam verus of Sixtus V (3 December 1586), he assumed the position of protopriest of the College of Cardinals. He participated in the conclave of 1691 which elected Pope Innocent XII and became Cardinal-Priest of the Church of Santa Prassede later that same year.
In the political rivalry between France and Spain Maidalchini initially aligned himself with Spain. However, leaders of Spanish faction at Rome showed him so little respect that he eventually changed the side. In the papal conclave of 1655 he was still counted among the members of Spanish party, but subsequently became one of the most faithful adherents of the Kingdom of France in the College of Cardinals.
- The majority of the sources consulted (George L. Williams: Papal Genealogy: The Families And Descendants Of The Popes McFarland, 2004; Eleanor Herman: Mistress of the Vatican: The True Story of Olimpia Maidalchini: The Secret Female Pope, William Morrow, 2008 ISBN 0-06-124555-0; and Ludwig von Pastor: History of the Popes. Vol. 30. London: 1940, p. 39) agree that he was in his 17th year when promoted to the cardinalate. S. Miranda: Consistory of October 7, 1647, citing Berton's Dictionnaire des cardinaux, says that he was born on 21 April 1621. However, on the other place Miranda himself remarks that Berton's work should be used with the great caution because of the numerous errors it contains. Lorenzo Cardella, Memorie storiche de' cardinali della Santa Romana Chiesa, vol. VII, Rome 1793, p. 80 explains that some sources give 1621 as the year of his birth but this goes back to the typographical error in the renewed edition of Ciacconius' Vitae et res gestae Pontificum Romanorum et S.R.E. Cardinalium (1621 instead of 1631).
- Contemporary, John Bargrave, states he was no older than 18 when he was made a cardinal, giving credence to the accuracy of a 1631 birth.
- Mistress of the Vatican: The True Story of Olimpia Maidalchini: The Secret Female Pope by Eleanor Herman (William Morrow, 2008) ISBN 0-06-124555-0
- Pope Alexander the Seventh and the College of Cardinals by John Bargrave, edited by James Craigie Robertson (reprint; 2009)
- Court and politics in papal Rome, ed. G. Signorotto & M. A. Visceglia, Cambridge University Press 2002, p. 147-148; Ludwig von Pastor: History of the Popes. Vol. 30. London: 1940, p. 39.
- Time, space, and women's lives in early modern Europe by Anne Jacobson Schutte, Thomas Kuehn, Silvana Seidel Menchi (Truman State Univ Press, 2001)
- Eleanor Herman: Mistress of the Vatican: The True Story of Olimpia Maidalchini: The Secret Female Pope, William Morrow, 2008 ISBN 0-06-124555-0
- S. Miranda: Francesco Maidalchini
- Catholic Hierarchy: Francesco Cardinal Maidalchini
- Eleanor Herman: Mistress of the Vatican: The True Story of Olimpia Maidalchini: The Secret Female Pope, William Morrow, 2008 ISBN 0-06-124555-0; Ludwig von Pastor: History of the Popes. Vol. 31. London: 1940, p. 2.
- Ludwig von Pastor: History of the Popes. Vol. 31. London: 1940, p. 2.
- Ludwig von Pastor: History of the Popes. Vol. 31. London: 1940, p. 317-318 and 432; ibid, vol. 32, p. 2 and 527.