War remained the primary concern of the Toledos and therefore of Ferdinand. It was typical of the young Ferdinand’s impetuosity that he chose to go on his first military campaign, in 1524, without asking permission of anyone. The frontier fortress of Fuenterrabía was in the hands of the French and of Navarrese rebels. The sixteen year old went off to join the siege being conducted by Spanish forces under the command of the Constable of Castile, Iñigo de Velasco. After the fortress was recovered late in February 1524, Ferdinand returned home briefly but was sternly reprimanded by Duke Fadrique [his grandfather] for his initiative.
All the same the incident served to enhance the young soldier’s reputation. A chronicler reports that ‘the Constable ordered Don Ferdinand of Toledo, grandson of the duke of Alba, to take charge of the town and its fortress, and though he was still young he began to do so with every evidence of being a worthy and brave soldier.’ The post of governor of Fuenterrabía was the first official appointment of his career.
Henry Kamen, The Duke of Alba (New Haven, Conn.: Yale University Press, 2004), 8.
Short Stories on Honor, Chivalry, and the World of Nobility—no. 351