The marriage, which reconciled the Barberini and Pamphili families, was engineered by Guistiniani's maternal grandmother, Olimpia Maidalchini, and Barberini's uncle, Cardinal Antonio Barberini, several years after the Barberini were forced into exile by an investigation instigated by Pope Innocent X following the Wars of Castro. Maidalchini, realizing her influence over Pope Innocent was waning, arranged the marriage to facilitate a return of the Barberini to Rome in order to curry favor with a number of the Barberini family's cardinals. The Barberini, too, were keen to return to Rome and were enthusiastic about Maidalchini's plan to marry Pope Innocent's grand-niece, Guistiniani, into their family.