“The Taking of Pamplona”, a painting by Horace Vernet depicting an episode of the French intervention against the Trienio Liberal. Public domain image.
The 19th century in Europe was an era of significant transformation, marked by a series of revolutions that reshaped the continent’s political and social landscape. Even though the French Revolution and the Napoleonic Era had been ultimately defeated, the liberalism espoused by them endured and represented a formidable challenge to the autocratic order of the Concert of Europe. After 1815, restored monarchies could repress revolutionary governments. The memory of constitutions, representative assemblies and political citizenship still survived in pamphlets, clubs and military circles.
In the 1820s, the first wave of revolutionary movements since Napoleon’s defeat in 1815 broke out. According to the historian James Billington, the movements of this decade happened in the peripheries of the continent, in traditional societies that had not yet begun the Industrial Revolution. That geography mattered: liberal revolt first advanced where imperial weakness, military grievance, colonial disruption, and memories of Napoleonic reform gave constitutional activists room to act before the great powers could agree on a response.
These revolutions also revealed a new political grammar. Officers and civilian liberals borrowed symbols from the French revolutionary tradition, while exile networks and secret societies helped ideas cross borders. They usually demanded written constitutions rather than social revolution. Their enemies therefore presented them as a threat to monarchical legitimacy, while their supporters described them as the completion of promises already announced in 1789 and 1812. For that reason, the decade should be read as a test of the post-Napoleonic settlement: governments tried to quarantine revolution, yet constitutional language kept moving through armies, ports, universities, Masonic lodges, and newspapers.
These were the main revolutions of the decade:
Trienio Liberal in Spain
During the Napoleonic Era, French troops had invaded Spain and had overthrown both King Charles IV and his son Ferdinand VII in the abdications of Bayonne, in 1808. Napoleon’s brother, Joseph Bonaparte, was installed on the Spanish throne.
Joseph attempted to rule the country with the Constitution of Bayonne, a document he crafted to secure power for himself while ostensibly conceding to political liberalism. Some Spaniards accepted the new regime, while others gathered in governing juntas and eventually relocated to Cádiz under British protection. There, amid war and imperial crisis, they proposed the Spanish Constitution of 1812. The importance of La Pepa lay in the way it joined anti-French patriotism to liberal principles. It defended constitutional monarchy, national sovereignty, a representative Cortes, legal equality and individual rights. It also claimed authority over Spain’s overseas territories, which made the imperial dimension of Spanish liberalism impossible to separate from the European one.
Once back on the Spanish throne in 1813, Ferdinand VII restored absolutist rule. His decision to abolish the Constitution of Cádiz did not simply reverse a legal text; it targeted the networks of soldiers, officials, and urban liberals who had defended constitutional government during the war. Repression pushed many of them into conspiracy, and the army became a particularly important setting because troops awaiting service in the American wars were angry, politicized, and close to the ports through which imperial authority was supposed to be restored.
In 1820, a military uprising led by Rafael del Riego forced Ferdinand to reinstate the Constitution of Cádiz, marking the beginning of the Trienio Liberal (1820-1823). Reformers reopened public debate and limited censorship. They also tried to reshape municipal government, taxation and church property. The Trienio Liberal showed both the promise and fragility of Spanish constitutionalism. It could mobilize cities and soldiers, yet it remained vulnerable to royal obstruction at court, resistance in the countryside and foreign intervention. At the Congress of Verona in 1822, the European powers endorsed a response against the revolutionary government. French troops then intervened, suppressed the Trienio Liberal, and restored Ferdinand VII’s uncontested authority.
Liberal Revolution in Portugal
During the Napoleonic Era, Portugal had been invaded by French troops, what made the royal family flee to Brazil. The royals had left a British general, William Beresford, in charge of their continental affairs. Even after Napoleon was long gone, they did not want to return to Europe. Thus Brazil went from being a colony to being a part of the United Kingdom of Portugal, Brazil and the Algarves. This arrangement was highly beneficial to Brazilians, who ensured they would keep unfettered access to international trade. At the same time, the European subjects of the Portuguese Empire had much to complain about, for they were kingless and their economic dominance was being challenged by the former colony.
In 1817, field marshal Gomes Freire de Andrade led a conspiracy that aimed to oust Lord Beresford and introduce a constitution in the country. However, the movement was uncovered by the government and it ultimately failed.
In 1820, Portuguese discontent would motivate yet another rebellion — this time with far greater repercussions. Inspired by the Cortes of Cádiz and by the Spanish Constitution of 1812 (La Pepa) they drafted, the Portuguese staged a revolt demanding that King John VI ratify a constitution, return to Europe with haste, and reestablish the colonial pact — cutting off Brazil from foreign trade. The Portuguese revolution therefore fused two unstable grievances: Metropolitan liberals wanted constitutional government, and many also wanted to restore Lisbon’s commercial authority over Brazil. In the face of such troubles, the monarch promptly accepted the demands.
The return of John VI to Lisbon did not resolve the imperial contradiction. His son Pedro remained in Brazil, where local elites had benefited from open ports, higher political status and the presence of the court. When the Cortes tried to subordinate Brazil again, the dispute crossed from constitutional reform into imperial breakup. Brazil declared independence in 1822, and Pedro became its emperor, leaving Portugal with a constitutional movement that had unintentionally accelerated the loss of its largest overseas possession.
This outcome explains why the Portuguese case cannot be treated only as a European constitutional episode. The same revolution that tried to make the monarchy accountable also tried to reverse Brazil’s wartime elevation. That tension weakened liberal legitimacy across the Atlantic. For Brazilian elites, the Cortes looked less like a parliament of liberty than a metropolitan body seeking to restore dependency; independence became a way to preserve the autonomy already gained during the royal exile.
Within Portugal itself, the struggle also exposed how difficult it was to define sovereignty after years of emergency rule. Liberals wanted the king to accept limits, but they still needed the monarchy to authorize the new order. Absolutists rejected that compromise and framed constitutionalism as a foreign infection. The conflict therefore turned every institutional question into a loyalty test: who commanded the army, who spoke for the nation, and whether the crown could be bound by a written charter.
Nevertheless, over the following years, some absolutist factions reacted against the proposed constitution through the Vilafrancada and the Abrilada. Court politics, military loyalty, dynastic rivalry and the church all shaped the struggle over the monarchy’s limits. Portugal’s liberal revolution survived only after a long crisis in which constitutionalism, succession and empire became entangled; the victory of Maria II in 1834 closed one phase of that conflict rather than erasing it. Portugal would only regain its political equilibrium in 1834, when the absolutists finally surrendered to the rule of Maria II under an authoritarian constitution.
Greek War of Independence
Since the 15th century, there was a growing national consciousness among Greeks that lived under the Ottoman Empire. It was encouraged by the ideals from the Enlightenment and by a romantic revival of classical culture, known as Philhellenism. This ideological and cultural renaissance ignited the Greek population’s desire for a sovereign nation-state that reflected its legacy.
In 1821, the Greeks initiated their revolt against the Ottoman Empire. This was the first significant act of separation from Ottoman rule, marking the beginning of the Empire’s fragmentation in the Balkans. The Greek struggle quickly transcended local boundaries, attracting attention and involvement from major European powers. The rebellion became European for two linked reasons. Outsiders admired ancient Greece, and any change in Ottoman territory threatened to alter the balance among Russia, Britain, France and Austria. A national uprising therefore became part of the wider “Eastern Question”, the long diplomatic problem of how European powers should manage Ottoman weakness without giving one rival too much advantage.
Russia supported the independence, motivated by its strategic interests in accessing warm-water ports and weakening the Ottomans, even though it conflicted with the counterrevolutionary principles of the Holy Alliance. France viewed the Greek struggle through the lens of liberalism and nationalism, advocating for the redistribution of Ottoman territories for the greater benefit of European powers. Meanwhile, England’s approach was initially conservative, favoring the maintenance of the Ottoman Empire’s integrity but later shifting to support Greek independence under certain conditions.
The Greek cause also depended on the interaction between battlefield endurance and foreign diplomacy. Ottoman repression produced outrage abroad, while Greek divisions and military setbacks made outside intervention more decisive. In 1827, the naval battle of Navarino turned sympathy into coercive power when British, French and Russian fleets destroyed the Ottoman-Egyptian fleet. After that, the powers debated the form of the Greek state rather than whether the revolt could be ignored.
From 1828 to 1829, Russia waged war against the Ottoman Empire and compelled its sultan to sign the Treaty of Adrianople. Under that settlement, the Ottomans recognized Greek autonomy, accepted Serbian autonomy, and conceded Russian influence in the Danubian Principalities. British diplomacy then pushed the settlement toward a different balance. The London Conference of 1832 and the Treaty of Constantinople secured an independent Greece while preventing Russia from turning Greek liberation into exclusive strategic dominance in the eastern Mediterranean.
The success of the Greek revolt, as historian Eric Hobsbawm noted, was due to a blend of popular mobilization and favorable diplomatic conditions. The widespread Philhellenism in Europe played a crucial role, as Greece became a symbol and inspiration for international liberalism. Greek independence also changed the meaning of liberal victory in the 1820s: unlike Spain or Portugal, it was not only a constitutional dispute inside an existing monarchy, but the international recognition of a new national state.
Conclusion
The revolutions of the 1820s were the beginning of a tide in the direction of more republican or democratic forms of governance in Europe. In Spain, liberal advances were soon reversed by the authoritarian tendencies of King Ferdinand VII. In Portugal and Greece, on the other hand, liberalism ultimately prevailed — but not without controversies, such as the independence of Brazil and the interference of foreign powers.
Their deeper importance lies in the way they connected local grievances to continental politics. Spanish officers rebelled against absolutism while the monarchy tried to recover an empire in the Americas. Portuguese liberals demanded a constitution while trying to restore a colonial hierarchy that Brazil no longer accepted. Greek insurgents fought for national independence, yet their success depended on the calculations of powers that feared both revolution and Russian expansion. The 1820s therefore exposed the limits of the Concert of Europe. The restored order could defeat some revolutions, negotiate with others and unintentionally make national self-determination part of European diplomacy.
The decade also left a practical legacy for later revolutionaries. Defeat in Spain did not make constitutionalism disappear; it taught liberals that armies, courts and foreign alliances could decide the fate of domestic reform. The Portuguese crisis showed that political liberty could be compromised by imperial nostalgia. The Greek case suggested that national movements could win when local mobilization coincided with the strategic interests of stronger states. In the 1830s and in 1848, new revolutions would emerge, continuing this tendency.
That is why the revolutions of the 1820s are best understood as beginnings rather than isolated failures or triumphs. They made constitutional language ordinary, tied liberal politics to national questions, and forced conservative governments to respond to movements that could no longer be dismissed as a French exception. Their mixed outcomes also made later insurgents more attentive to timing, diplomacy, military loyalty, and the international setting of domestic reform.