From xkazemg:
The strong influence and power of Spanish navy has enabled Spain to become the foremost kingdom in Europe during its Golden Age. But this powerful navy force has always been relying on the Frontera Family, which was traditionally tied to serve the Spanish royal. But this tie was under the threat of being broken when kingdom was under the reign of Philip II.

Leon became the new leader of Frontera Family when he was just 12 years old. Although Philip II has shown great respect to his deceased father, the king paid little attention to the “child leader”.