Ferdinand was the eldest child of Prince Alfonso, Count of Caserta and his wife Princess Maria Antonietta of Bourbon-Two Sicilies.

[3] But Henri, Count of Paris, upheld the claim of Ferdinand's younger brother, Prince Ranieri, Duke of Castro (1883–1973), contending that Carlos had renounced his rights of succession for himself and his descendants in 1901 when he married the Spanish heiress presumptive María de las Mercedes, Princess of Asturias.

The Count of Paris was well aware that his own claim to the French throne depended on the validity of the renunciation in 1713 of Philip V of Spain, in favor of the junior House of Orléans.

[3] In 1900, Prince Carlos had executed the Act of Cannes, in anticipation of his marriage to María de las Mercedes, and in 1901 he became a Spanish subject and accepted the title of Infante.

[8] On 27 May 1915, he was promoted to Oberst à la suite of the Army and on 6 June 1915 he was named Ordonnanzoffizier (aide-de-camp or orderly officer) on the staff of the newly-formed 11th Bavarian Infantry Division.