[2] His religious career was abandoned in 1844 when his uncle King Louis Philippe of France proposed to marry Francis to the young Queen Isabella II of Spain.

The French ambassador to the Holy See who met the Count of Trapani at this time described him unfavorably as " very ugly, small, of sickly appearance, without expression of intelligence; and when I remember in what condition of health I saw Queen Isabella during my stay in Spain (she suffered from an acute form of eczema), I cannot help thinking that at least from the physical point of view, they could choose better".

His brother the Count of Aquila, his confessor, and the pro-Austrian party in Naples were all against the idea, thinking that he would be an instrument in King Louis Philippe's hands and that the Queen of Spain could not bear children.

However, after the fall of Narvaez's government in April 1846, and facing the lack of support in Spain for the project, Maria Christina chose her nephew the Duke of Cadiz as a husband for her daughter in an agreement with King Louis Philippe.

[9] During the short reign of his nephew King Francis II, Trapani, lacking in political acumen, provided him with little help in the critical time of the fall of the Kingdom of the Two Sicillies.