Castile Guide: From Iberia to Empire in the First 50 Years

Castile in 1337 is the rare start that is both strong and instructive. You sit in a defensible corner of Europe with exactly one direction to expand, a rich economy waiting to be organized, and a scripted dynastic route to uniting Iberia. The campaign teaches EU5’s core loop — estates, parliament casus belli, feudatories, colonization — with training wheels you’ll barely notice. Here is the first-50-years plan, including the one decision the community genuinely fights about.

Before you unpause

The capital question. The deepest published Castile guide moves the capital to Sevilla immediately and calls the historical choice “the Toledo trap”: central Spain has weaker terrain, goods, and market access, and a capital there overlaps coverage your governors already provide. The counter-camp swaps to Toledo for the central position and reports the move costs only a small stability hit. We follow the Sevilla line below — the south’s Guadalquivir trade position compounds hard once Granada and Morocco fall — but this is a fork, not a rule.

Governors. With the capital in Sevilla, put your first local governor in Valladolid to hold the northern power center, the next in Tortosa (Mediterranean and Aragon proximity), then Toledo for central coverage. Skip Morocco and Algeria — Sevilla’s own proximity already reaches them. As overseas holdings appear, naval governors in hubs like Tunis or Naples pay off. An independent tip worth considering: release distant Galicia as a subject and let it convert pop culture to Castilian for you.

Forts and army. Delete most starting forts; keep Sevilla, Córdoba, Toledo, Burgos, and Murcia. The southern priority is not cosmetic — if Muslim armies siege your south, they begin enslaving your population. Delete your starting infantry and recruit cavalry instead: in Age I your levies supply all the infantry you need, and manpower flows mainly from the sergeantry.

Economy. Fix shortages first. Then invest along Castile’s actual advantages: construction goods (glass, wood, masonry) to cut building costs, textiles (unique national bonuses), and jewelry (you start with two silver provinces). Add bailiffs in your highest-base provinces, and diversify once cash flow is stable.

Estates and the heir. Keep nobility power above 50% through the first decade or two: it gates the Fuero Viejo de Castilla event (community reported: +0.10 legitimacy and +5% noble satisfaction, available only in the first hundred years). And plan around Pedro — your starting heir is scripted to be a problem, trailing negative modifiers and legitimacy-draining events. Replace him when you can.

Years 0–15: the conquest ladder

Ally France early — max relations, profess trust repeatedly, then ally. France is your coalition insurance for everything that follows. Keep the Pope warm too. Rival Aragon, Granada, and Morocco; leave Portugal alone for now. Start a spy network in Morocco and keep stealing their maps — they chart your later road to Mali. Push military quality to 10, the threshold for professional armies.

The ladder runs:

1. Navarra and Aquitaine. Your first parliament can hand you both CBs. Make Navarra a feudatory, take Bayonne from Aquitaine and gift it to Navarra — England is usually too deep in the Hundred Years’ War to respond. Take nothing more from Aquitaine; over-eating here angers France and raises your antagonism before the wars that matter.
2. Granada. Fabricate at the next parliament, vassalize, take Málaga, release another feudatory.
3. Morocco. The Threat of Morocco event usually hands you the CB (if you didn’t rival Portugal); fabricate your own if it hasn’t fired in 10–15 years. Morocco brings Tunis — let their armies land in Iberia and destroy them on arrival, then cross over and take the north plus Sus, your future stepping stone toward the gold.

Years 15–35: the Iberian Union

After Morocco, rival Portugal. Because Navarra left Aragon short of friends, Aragon usually allies Portugal — which is exactly what you want. Wait for the Portuguese ruler to die: that triggers the Claim Throne CB, and with Aragon co-belligerent, one war can enforce your claim on both crowns. With France alongside it’s trivial; alone it’s still manageable. Expect the union to complete a generation late — your dynasty typically lands on their throne first.

When your own founding ruler dies, the Castilian Civil War fires. Side with the legitimate king: the other side risks your unions over Aragon and Portugal, and your allies will largely win the war for you anyway.

Years 35–50: gold and God

Age II priorities from the community line: take the admin focus and rush Deus Vult — it becomes your workhorse CB for the rest of the game. Expand along the Maghreb with small two-province feudatories that convert religion and culture passively. Stand up professional armies (armories, tier-two levies) once quality passes 10. Then go where the gold is: Mali first, then ports toward Zimbabwe and Akan. By Age III you pivot to colonization — Central Brazil, Mexico, the Andes, and Ecuador for precious metals, the Moluccas for cloves — choosing between the diplomatic focus (stronger colonization) and admin focus (passive cultural conversion and tech).

Common death spirals

Sources checked

The main line above follows the wiki’s community starting guide, whose author is the same 450-hour Castile specialist behind the r/EU5 guide thread — deep, but one voice, so we cross-checked against an independent tips thread and present the capital fork rather than settling it. The wiki’s cleanup flag on that guide concerns formatting, not accuracy, per the wiki’s own editors. Event names, thresholds (nobility 50%, quality 10), and the Catholic empire-rank claim are community-reported and patch-sensitive; the country data and formation blocks are wiki-verified. Castile headlines the Across the Pillars DLC this fall — expect a major revision of this page then.