The early 19th century in Europe was a tumultuous period, dominated by the ambitious campaigns of Napoleon Bonaparte. Within this grand tapestry of the Napoleonic Wars, a particularly brutal and strategically significant conflict unfolded on the Iberian Peninsula, known as the Peninsular War (1807–1814). This drawn-out military struggle saw the combined forces of Spain, Portugal, and the United Kingdom fiercely resist the invading and occupying might of Napoleon's First French Empire. For Spaniards, this period is synonymous with their Spanish War of Independence, a deeply nationalistic and formative moment in their history.

The Genesis of Conflict: Napoleon's Iberian Ambitions

The war's origins trace back to 1807 when French and Spanish armies initially marched through Spain to invade and occupy Portugal, a traditional British ally. However, the situation dramatically escalated in 1808 as Napoleonic France, once an ally to Spain, turned its ambition westward. Emperor Napoleon Bonaparte orchestrated the forced abdication of both King Ferdinand VII and his father, Charles IV, from the Spanish throne. In their place, he installed his own brother, Joseph Bonaparte, as the new monarch and unilaterally imposed the liberal but foreign Bayonne Constitution. This blatant disregard for Spanish sovereignty was met with overwhelming rejection by most Spaniards, who were unwilling to accept French rule. What followed was a bloody and relentless struggle to oust the invaders, transforming the conflict into one of Europe's first true wars of national liberation and marking the significant emergence of large-scale guerrilla warfare.

A Nation Divided, A Resistance Ignited

The spark that ignited widespread Spanish resistance was the infamous Dos de Mayo Uprising in Madrid on May 2, 1808. From that point, the conflict raged across the peninsula until April 17, 1814, culminating in the restoration of Ferdinand VII to the Spanish monarchy. The initial French occupation crippled the Spanish administration, causing it to fragment into quarreling provincial juntas. This tumultuous period remains etched in Spain's modern memory as its bloodiest event, claiming lives on a scale that, in relative terms, surpassed even the later Spanish Civil War. Amidst this chaos, a reconstituted national government, the Cortes of Cádiz—effectively a government-in-exile—fortified itself within the secure port city of Cádiz in 1810. Despite being besieged by a formidable force of 70,000 French troops, the Cortes managed to promulgate the liberal Spanish Constitution of 1812, a foundational document that would later become a cornerstone of European liberalism.

While the Cortes of Cádiz struggled to raise effective armies, British and Portuguese forces, under the brilliant leadership of then Lt. Gen. Sir Arthur Wellesley (who would later become the iconic 1st Duke of Wellington), secured Portugal. This served as an invaluable strategic base from which to launch campaigns against the French army and funnel much-needed supplies to the Spanish resistance. Meanwhile, Spanish regular armies, even after repeated defeats that pushed them to the peripheries, regrouped and, alongside the relentless Spanish guerrillas, effectively tied down vast numbers of Napoleon's troops. This combined pressure from allied regular forces and irregular partisan fighters restricted French control of territory, preventing Napoleon's marshals from fully subduing the rebellious Spanish provinces and leading to years of a grueling stalemate. The demoralized Portuguese army itself was meticulously reorganized and refitted under the command of Gen. William Beresford, appointed commander-in-chief by the exiled Portuguese royal family, and subsequently fought as a crucial part of Wellesley's formidable Anglo-Portuguese Army.

The Tide Turns: Allied Victories and French Retreat

The turning point arrived in 1812. As Napoleon embarked on his ill-fated and disastrous invasion of Russia, diverting significant resources and manpower from the Iberian Peninsula, Wellesley seized the opportunity. A combined allied army pushed deep into Spain, achieving a decisive victory against the French at the Battle of Salamanca and subsequently capturing the capital, Madrid. The following year, Wellesley delivered yet another crushing blow to King Joseph Bonaparte's forces at the pivotal Battle of Vitoria. With their grip on Spain rapidly loosening, the exhausted and demoralized French forces, under Marshal Jean-de-Dieu Soult, and no longer receiving adequate support from a depleted France, were pursued relentlessly by the armies of Britain, Spain, and Portugal. During the harsh winter of 1813–1814, Soult led a fighting withdrawal across the Pyrenees, marking the effective end of French occupation.

The "Spanish Ulcer" and Enduring Legacy

The prolonged years of fighting in Spain proved to be an immense burden on France's celebrated Grande Armée. Despite often winning pitched battles, the French were ultimately defeated by a combination of factors. Their communications and supply lines were severely stretched and constantly harassed by the partisans. French units were frequently isolated, ambushed, or overwhelmed by locals fighting an intense guerrilla war. Napoleon himself, recognizing the debilitating drain on his resources caused by a conflict he had unwittingly provoked into a "total war," famously dubbed it the "Spanish Ulcer." This relentless attrition, coupled with the strategic brilliance of Wellington and the steadfastness of his Anglo-Portuguese and Spanish allies, contributed significantly to Napoleon's eventual downfall across Europe. The war and revolution against Napoleon's occupation not only gave birth to the Spanish Constitution of 1812 but also shattered the social and economic fabric of both Portugal and Spain. It ushered in an era of profound social turbulence, increased political instability, and economic stagnation that would plague the Iberian Peninsula for decades. Devastating civil wars between liberal and absolutist factions, often led by officers hardened by their experiences in the Peninsular War, continued to rage in Iberia until as late as 1850. Furthermore, the cumulative crises and disruptions caused by invasion, revolution, and restoration had far-reaching consequences across the Atlantic, directly leading to the independence of most of Spain's American colonies and the eventual independence of Brazil, which remained a monarchy after severing its ties with Portugal.

A Glimpse from the Front: The Battle of Barrosa

Among the many engagements of the Peninsular War, the Battle of Barrosa (also known as the Battle of Chiclana or Battle of Cerro del Puerco), fought near Chiclana on March 5, 1811, offers a vivid illustration of the tactical complexities and bravery displayed. This battle was part of an ambitious, though ultimately unsuccessful, maneuver by an Anglo-Iberian force aimed at breaking the tenacious French siege of Cádiz. Cádiz had been under French investment since early 1810, remaining accessible only from the sea. However, in March 1811, a temporary reduction in the besieging French army offered the combined British and Spanish garrison an opportunity to lift the siege. A substantial Allied strike force was transported south from Cádiz to Tarifa, planning to attack the French siege lines from the rear. Marshal Victor, commanding the French forces, was well aware of this Allied movement and skillfully redeployed his troops to set a cunning trap. He positioned one division squarely on the road to Cádiz, effectively blocking the Allied line of march, while his two remaining divisions fell upon the single Anglo-Portuguese rearguard division, commanded by Sir Thomas Graham.

What followed was a fierce and desperate battle fought on two distinct fronts. Despite being heavily outnumbered, the British forces, through sheer discipline and tenacity, succeeded in routing the attacking French divisions. They even managed to capture a coveted regimental eagle, a symbol of immense pride. However, a critical lack of timely support from the larger Spanish contingent prevented this tactical victory from becoming an absolute triumph. The French were able to regroup and swiftly reoccupy their siege lines around Cádiz. Consequently, while Graham's forces had won a notable battlefield victory, it unfortunately had little strategic effect on the broader war, to the extent that Marshal Victor was able to claim the engagement as a French success, as the siege of Cádiz remained firmly in place until it was finally lifted on August 24, 1812.

Frequently Asked Questions About the Peninsular War

What was the Peninsular War?

The Peninsular War (1807–1814) was a major military conflict fought on the Iberian Peninsula, primarily involving Spain, Portugal, and the United Kingdom against the occupying forces of Napoleon's First French Empire during the broader Napoleonic Wars. It is often regarded by Spaniards as their War of Independence.

Who were the primary belligerents in the Peninsular War?

The main opposing forces were the First French Empire, led by Napoleon Bonaparte and his generals, against a coalition of Spain, Portugal, and the United Kingdom. Various local militias and guerrilla fighters also played a crucial role on the Allied side.

What was the "Spanish Ulcer"?

The "Spanish Ulcer" was Napoleon Bonaparte's own term for the Peninsular War. He used this phrase to describe the draining, debilitating effect the prolonged and brutal conflict had on his Grande Armée, which suffered immense casualties and diverted critical resources away from other fronts in Europe due to relentless guerrilla warfare and sustained Allied opposition.

Who was the Duke of Wellington during this conflict?

The 1st Duke of Wellington, then known as Lt. Gen. Sir Arthur Wellesley, was the principal commander of the British and Anglo-Portuguese forces throughout the Peninsular War. His strategic brilliance and tactical prowess were instrumental in repeatedly defeating the French armies and ultimately driving them out of the Iberian Peninsula.

What was the significance of the Cortes of Cádiz?

The Cortes of Cádiz was a national assembly, effectively a government-in-exile, that convened in the besieged city of Cádiz from 1810 to 1814. It famously promulgated the Spanish Constitution of 1812, a highly liberal document that championed national sovereignty, separation of powers, and individual rights, influencing subsequent liberal movements across Europe and Latin America.

How did the Peninsular War impact Spain and Portugal in the long term?

The war left Spain and Portugal devastated, with severe economic and social disruption. It ushered in decades of political instability, marked by civil wars between liberal and absolutist factions, and contributed significantly to the independence movements in Spain's American colonies and Brazil, fundamentally reshaping the global map.