He served with distinction in Spain in 1823, where he was promoted to the rank of lieutenant-general. After two years at court of Berlin, he became the French ambassador in Madrid, where he negotiated in 1828 the settlement of the Spanish debt. When the July Revolution in 1830 compelled his retirement, the Spanish king Ferdinand VII in recognition of his services made him a grandee of Spain, with the title of Duke of Almazán.[1]
He then joined the circle of former King Charles X's widowed daughter-in-law, Caroline Ferdinande Louise, duchesse de Berry, at Naples, and arranged her escapade in Provence in 1832. Saint-Priest was arrested, and was only released after an imprisonment of ten months. Having arranged for an asylum in Austria for the duchess, he returned to Paris, where he was one of the leaders of Legitimist society until his death, which occurred at Saint-Priest, near Lyon.[1]