Service to the King and Loyalty to the Duke. The Castro Family in the Faction of the Duke of Lerma

The Castro family, Counts of Lemos since the Middle Ages, reached the zenith of its power and prestige during the reign of Philip III. The political link generated by the marriage between the sixth Count of Lemos and one of the Duke of Lerma’s sisters allowed the sons of the couple to play a leading role within the faction led by the favourite of the King. The article aims to compare the work of the seventh and the eighth Count of Lemos, especially during their viceregal mandates in the Italian lands, highlighting the way in which they were able to contribute to the faction’s objectives and strategies. This comparison will show how, in the factions of early modern Europe, characters of very different abilities and ambitions could act together, being used each and every time according to their own skills and the needs of their families and allies.