Infanta Urraca Fernández in Crusader Kings 3 is the eldest child of the late King Ferdinand the Great, and she is the Countess of Zamora. Despite being the eldest child, Infanta Urraca’s three younger brothers inherited the kingdoms of Galicia, León, and Castille due to succession laws and confederate partition laws favoring male heirs. Infanta Urraca is Countess under her brother and lover, King Alfonso VI. She has claims on all of her brothers' kingdoms, and the gameplay decisions available to her are: Unite the Spanish Thrones, form Portugal, or create a Cadet Branch and forge her own dynasty.
Crusader Kings 3 ranks Infanta Urraca's gameplay as hard, but uniting the Spanish thrones can be simple. Through strategy, skullduggery, and some luck, Infanta Urraca can ascend to the throne of Castille and take over the Duchy of Coimbra. Schemes and murder plots can sometimes go awry, and vassals can make things more challenging as Infanta Urraca seeks to up the Crown Authority and keep control of her realm. However, achieving the Unite the Spanish Thrones achievement isn’t too hard in comparison to forming Portugal.
4 Kill Her Darlings
Despite her strong Stewardship skill, the strongest approach to uniting the Spanish Thrones is through the Intrigue lifestyle. Scandalously, Infanta Urraca has an incestuous relationship with her brother, King Alfonso VI. This relationship should be culled, as well as King Alfonso VI. In fact, Infanta Urraca needs to enact murder schemes on all her brothers and their children.
At the very least, players must break up the incestuous lovers' relationship. Any resulting children could have negative traits due to inbreeding, and it would be disastrous for vassals and other peoples’ opinions towards Infanta Urraca if this were to be found out.
3 Intrigue And Congenital Traits
While choosing the Intrigue lifestyle will make the murderous schemes easier, this can be achieved before Infanta Urraca receives her first perk point. It won’t happen in every playthrough, and many times her schemes will be found out, or people will expose her crimes and blackmail her. This is still the easiest way to end up ruling Castille, which will set up the decision to Unite the Spanish Thrones. The courtier Belidu Dolfos has a fantastic Intrigue skill value of 21, and players should appoint him as Infanta Urraca's Spymaster.
Infanta Urraca has the Chaste trait, which has a fertility penalty, so this will need to be circumvented. With enhanced spousal fertility traits, such as Fecund, Comely, Handsome, and Beautiful, a boost from the Like Weeds in a Garden perk from the Intrigue lifestyle, and Infanta Urraca’s spouse as her lover or soulmate, there should be a handful of children before Infanta Urraca cannot have them anymore. Children, beyond furthering the dynasty, are helpful for powerful alliances and prestige gain.
2 Alliances And Angry Vassals
Infanta Urraca will face many rebellions during her rule over Castille. Vassals will want a lowered crown authority to reduce control over them, people will try and dissolve the realm, and there will be factions for claimants to the throne. Vassals rising up against her will be inconvenient at best and detrimental to her reign if this happens in the middle of another war, like a struggle clash for Coimbra as part of Galicia. It is important for vassals to have a positive opinion of Infanta Urraca to reduce the chance of rebellions and to reduce any discontent that would lead to factions against her.
Allying with powerful entities like England, Tuscany, and The Holy Roman Empire will give Infanta Urraca enough soldiers to staunch any rebellions and launch any wars she wishes to declare. Alliances with powerful and large armies will be the best defense against any rebellions. The resulting imprisoned vassals can be executed after they lose their faction wars, which will increase Infanta Urraca's dread and make it more difficult for her vassals to go against her. If vassals want to lower the Crown Authority, prevent this at all costs. Infanta Urraca losing prestige or money to fight these wars is worth it, as it takes 10 years to increase or decrease the Crown Authority again. Conceding the Crown Authority will majorly set progress back for Infanta Urraca.
1 It’s Her Royal Prerogative
Study the Royal Prerogative fascination to unlock the ability to enact both the High Crown Authority and the Absolute Crown Authority laws. This needs to be studied as early as possible and can be found in the Early Medieval section within the culture menu.
Have whoever is Steward in the counsel convert the culture of counties in Castille to the Castilian culture and promote development in those counties. Increasing those two values will speed up the progress of the Royal Prerogative fascination. Once the fascination has been discovered, and Infanta Urraca passes a higher Crown Authority, then it is possible to unite the Spanish Thrones.
Crusader Kings 3 is available on PC, PlayStation 5, and Xbox Series X/S.