Castile was a kingdom whose union with Aragon helped form Spain, and whose Cortes offered only a limited check on royal power. Its political history illustrates the book’s central argument that small differences in institutions can become decisive when major economic opportunities arrive: while England’s Parliament became a source of constraint on the Crown, Castile’s representative assembly was sidelined as Spanish absolutism strengthened.

Union and Imperial Expansion

In 1492, the crowns of Castile and Aragon were joined through the marriage of Isabella and Ferdinand. The same year, Granada fell at the end of the Reconquest, and Christopher Columbus reached the Americas on a voyage funded by the monarchs. Subsequent dynastic marriages and inheritances expanded the union’s reach. After Isabella’s death in 1504, her daughter Joanna became queen of Castile; Joanna’s son Charles was crowned ruler of Castile and Aragon in 1516. He later inherited the Netherlands and Franche-Comté, and, after the death of his grandfather Maximilian I in 1519, the Habsburg territories in Germany. As Charles V, he became Holy Roman Emperor, presiding over a far-flung monarchy that continued the project of consolidating absolutist rule.

American silver strengthened the Crown’s resources. Large deposits were found in Guanajuato by the 1520s and soon afterward in Zacatecas; the conquest of Peru added further wealth, including the monarchy’s share of conquest proceeds and mining revenue. Silver from Potosí, discovered in the 1540s, flowed into the Spanish king’s coffers. This revenue helped sustain royal power, but it did not produce the broad political and commercial participation that might have made colonial trade a source of wider institutional change.

The Cortes and the Crown

Castile’s Cortes represented the kingdom’s estates and had to be summoned to assent to new taxes. Yet its reach was narrow: by the fifteenth century, it represented only eighteen cities, each sending two deputies. Unlike the English Parliament, it did not represent urban and rural groups across the country. It could not legislate, and even its role in taxation was limited. It therefore never became a broad arena in which varied interests could effectively constrain absolutism.

The Crown’s demands for revenue exposed this weakness. In 1520, Charles V asked the Cortes for increased taxation. Urban elites used the occasion to press for wider changes to the assembly and its powers, and their opposition escalated into the Comunero Rebellion. Charles crushed the rebellion with loyal troops. The contest over taxation continued through the sixteenth century, but the monarchy ultimately prevailed. After 1664, the Cortes did not meet again until it was reconstructed during the Napoleonic invasions, almost 150 years later.

The contrast with England was consequential. After the defeat of absolutism there in 1688, Parliament gained control over state policy. Many parliamentarians had investments in trade and industry and thus an interest in enforcing property rights; they also supported taxation and spending for purposes they considered valuable, especially a stronger navy to protect overseas commerce. Castile’s political institutions did not develop into a comparable constraint on royal authority.

Trade, Monopolies, and Divergence

Spain organized colonial trade through a guild of merchants in Seville. The guild controlled commerce with the colonies and ensured that the monarchy received its share of American wealth. Trade within the empire was also heavily regulated: merchants in New Spain, for example, could not trade directly with merchants in New Granada. These restrictions limited the growth of a broad merchant class and reduced the potential prosperity generated by trade, while helping ensure that precious metals continued to reach Spain.

The book places Castile’s institutional trajectory within a wider comparison of England, France, and Spain. Atlantic trade was a critical juncture: it created new profits and opportunities, but their effects depended on who could claim them and how political power was organized. In England, traders who were relatively independent of the Crown gained wealth and pressed to restrict royal prerogatives. In Spain, colonial trade remained closely controlled by the monarchy and its allies. The distinct distribution of commercial gains therefore reinforced distinct political paths.

This account does not treat the divergence as inevitable. Institutional differences could begin small and accumulate through conflict and contingent outcomes; a disruptive event could then make those differences much more consequential. Castile’s limited Cortes, the Crown’s victory over its challengers, and the monopolized structure of colonial trade together help explain how Spain’s absolutist institutions consolidated, while England moved toward greater pluralism. In the book’s framework, the fortunes of these societies emerged not simply from geography, culture, or superior policy knowledge, but from the institutions that shaped power, incentives, and the distribution of wealth.