Why a Spanish court in Mexico wouldn't have stopped US expansion

A Spanish court in Mexico would not have halted US expansion

In 1807, as Napoleon's troops entered the Iberian Peninsula, the Portuguese royal family fled to Brazil. The Spanish court, however, ended up held captive in Bayonne. This asymmetry is the starting point of a long-circulating counterfactual scenario: if the Bourbons had settled in Mexico, would the viceroyalty have preserved its territory? The most ambitious thesis argues that Mexico would have reached the Mississippi and that Brazil is large today thanks to the relocation of the Portuguese court, which provided it with a top-tier geopolitical education.

The problem is that the comparison falls apart on several fronts. Brazil did not share a border with a demographically expanding power like the United States, and its inland expansion was already well underway: the *bandeirantes* (frontier explorers) were already pushing beyond the Treaty of Tordesillas in the 16th century, long before the Portuguese court crossed the Atlantic.

Demographics as a decisive factor

The most significant argument in this analysis is population. Mexico was a country of barely seven million inhabitants compared to over twenty million in the United States during the 1846-1848 war, and most of those seven million were concentrated between Veracruz and Jalisco. Settling and defending two million square kilometers—four times the size of Spain—with such a base was, at best, a pipe dream.

Anglo-Saxon migration toward Texas had begun even before Mexican independence. When the territory gained independence, American settlers were already established. Geography did not help either: while traveling from the Mexican interior to Texas required crossing ridges and mountains, the terrain from Louisiana or Oklahoma was flat. This facilitated the mobilization of the US Army during the war.

Why Brazil succeeded while Mexico failed?

The comparison with Brazil is misleading for a fundamental reason: Portugal moved its court to a colony that had no neighbors capable of overwhelming it. Mexico, on the other hand, shared a border with a country that doubled its population and was growing at an exponential rate. Furthermore, Brazil's expansion into the interior was supported by the slave trade: hundreds of thousands of people brought by Portuguese slave traders created a demographic bomb that would consume the center of the South American continent regardless of where the king was located.

Some argue that a Mexico with the court in America would have had an elite with greater geopolitical knowledge and a more orderly emancipation. The most optimistic scenario assumes that the king, present in the territory, would have neutralized the power vacuum argument that justified the *juntas americanas* (local governing councils). However, this is countered by the fact that the Portuguese court returned to Lisbon in 1821 and Brazil gained independence in 1822: the monarch's presence did not guarantee continuity.

The army that never arrived

Spain attempted to retake Mexico in 1829. It sent a vanguard force of 3,500 men, of whom only about 3,000 landed trinc a shipwreck. Reinforcements never arrived. This episode summarizes the monarchy's actual capacity to project military power in America after independence.

The Peninsular army had around 100,000 soldiers in 1820, but it was immobilized in garrisons, divided between absolutists and liberals, with a massive desertion rate. The expedition to the Río de la Plata, involving nearly 30,000 troops and sailors, was never deployed as planned. The journey relied on sail; by 1895, when Weyler mobilized 200,000 soldiers to Cuba, steamships had completely changed logistics.

The annexation the United States rejected

A detail that is often forgotten: the United States did not annex all of Mexico after the war. American politicians argued it was impossible to integrate millions of people with a different culture—Catholics, Spanish speakers, and a majority mestizo or indigenous population. The underlying reason was to maintain the balance between slave and abolitionist states in Congress.

This same balance explains why territorial expansion peine in stages rather than all at once. The 1846-1848 war was a conquest, and that creates tension in the American founding narrative: there are hardly any films about it. The battles were unequal, and US logistics operated with an efficiency that the Mexican side could not match.

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Ultimately, the most unsettling fact is not the one being debated, but the one being forgotten: in 1900, Brazil had 18 million inhabitants for a territory twenty times larger than Spain, which also had around 18 million. The Brazilian demographic bomb exploded after independence, not before. If the relocation of the court had been the decisive factor, the numbers would not add up.