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Peninsular War

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Peninsular War

In 1808 Napoleon, the Emperor of France, was at the peak of his power. He had defeated Austria and Prussia and signed a peace treaty with Russia, ending hostility with them. He had established the continental system and weakened the arch-enemy of France, Britain.

But only six years later, Napoleon was forced to abdicate as Emperor. It was the Peninsular War that marked the beginning of the end of Napoleon's reign. Though Napoleon was confident he would be able to conquer Portugal and Spain quickly, he ended up embroiled in a long and costly war. Let's explore how this shocking reversal of fortunes came about.

Peninsular War Timeline

Date Event
Napoleon Bonaparte became the first Emperor of France.
The Battle of Trafalgar saw the defeat of French and Spanish forces at the hands of the British.
The Treaty of Fontainebleau was signed between France and Spain, declaring that Portugal was to be divided between them into three regions. That same year, France invaded and captured Lisbon.
Napoleon betrayed his alliance with Spain and sought to bring it under French control. French forces occupied northeastern Spain.
The beginning of the Iberian Revolt.
Napoleon began his march toward Moscow and was defeated in Russia.
Due to his defeat, Napoleon was forced to withdraw some of the French forces located in Spain and Portugal. This gave the Iberians the opportunity to begin their counter-offensive and retake Spain and Portugal.
The unified forces of Portuguese, Spanish and British defeated the remaining French armies.
The War of the Sixth Coalition began.
Napoleon was finally defeated and the First French Empire fell. Spain and Portugal were freed from the French threat and Napoleon was exiled to the island of Elba.

Peninsular War Definition

The Peninsular War was called as such because it was fought on the Iberian Peninsula, that was made up of Spain and Portugal.

Peninsular war.Map of France,Spain & Portugal.StudySmarterMap of France in the north-west and Spain and Portugal in the south-east. Note how close France and Spain were, even sharing a border. By Whiplashoo21. Creative Commons License. CC-BY-SA-4. Source: Wikimedia Commons.

Peninsular War Summary

In the beginning, Spain was on good terms with Napoleon and France. But in 1808 Napoleon betrayed Spain by invading the country and putting his brother, Joseph, on the throne. Napoleon's war in the Spanish and Portuguese Peninsular marked the beginning of the end. It would spark his demise in mainland Europe and embroil him in a long and costly war. His defeats in Spain and Portugal proved to the rest of Europe that Napoleon’s armies were no longer invincible.

But what changed to sour Napoleon's alliance with Spain? It was really two factors that turned Spain from an ally into a liability for Napoleon: its political instability and its poor military contributions.

Peninsular War Background Napoleon

Napoleon Bonaparte became the first Emperor of France in 1804. He was an exceptionally successful military commander and was a popular figure in France. From the outset of his reign as Emperor, he was embroiled in multiple international conflicts, stemming from previous wars.

Peninsular war.Painting of Napoleon,Emperor of the French.StudySmarterPainting of Napoleon, Emperor of the French, by Jacques-Louis David in 1812. Public Domain. Source: Wikimedia Commons.

If Napoleon was facing war on all sides, why then in 1808 did he decide to invade Spain, a country that was already compliant to French interests? The leading Napoleonic historian David Chandler1 argues that the Peninsular War was a show of Napoleon's sense of invincibility. In 1808 France was at the height of its power, defeating Austria and Prussia and signing a peace treaty with Russia. He had established the continental system, weakening France's old enemy, Britain. Though the Battle of Trafalgar was certainly a blunder, Napoleon's expansion of the French Empire was well underway.

What was the Continental System?

The Continental System was a blockade specifically designed to weaken and eventually paralyse Great Britain. It did this by blocking off any trade routes that were controlled and used by Great Britain. Napoleon understood that economically weakening Britain would make France the greatest economic power in not only Europe but the world.

What the Peninsular War, fought in Spain and Portugal, represented was the beginning of the end of Napoleon's reign as Emperor. It would prove to be the first of a series of blunders that eventually led to Napoleon's downfall in 1814.

Portuguese Peninsular War

Napoleon expressed his frustration towards Portugal. Portugal was one of Britain’s oldest allies and refused to join the Continental System. This alliance made it easier for Britain to bypass the Continental System's blockade via Portugal and its colonies such as Brazil.

An invasion became necessary to weaken Britain, France's arch-enemy. As a prerequisite to French invasion, the Treaty of Fontainebleau was signed between France and Spain in 1807. The treaty declared that the ruling monarchy was to be exiled and that Portugal was to be divided into three regions between France and Spain. Later that year, Portugal was invaded by the French and Spain and the capital Lisbon was occupied by French troops. The Portuguese monarchy and nobility fled to Brazil before the invasion.

Portuguese Peninsular War Spain Betrayed

Though Portugal and its capital Lisbon were captured, Napoleon did not stop there. Unannounced to Spain, Napoleon’s French troops crossed the Pyrenees in February 1808 and occupied the north of Spain.

The Pyrenees

The mountain range that separated the Iberian Peninsular from the rest of Europe. It sat on the border between France and Spain.

Stunned at this betrayal of an ally, the Spain swiftly began pulling its troops from Portugal. But why did Napoleon break France and Spain's alliance in the first place?

Spain's poor military led to resentment from Napoleon who believed they were not pulling their weight in the alliance. In particular, French and Spanish defeat at the hands of the British in the Battle of Trafalgar in 1805 tested their alliance.

Peninsular war.Painting of the Naval Battle of Trafalgar.StudySmaterPainting of the naval Battle of Trafalgar by J.M.W. Turner in 1822. Public Domain. Source: Wikimedia Commons.

What's more, Napoleon came to learn of Spain's backhanded dealings with Britain, long considered by France as its enemy. Spain's Prime Minister had proposed to Britain that it would abandon the alliance and invade France if Napoleon was weakened in future battles. This was compounded by the fact that Spain's internal political quarrels and corruption. Rivalry between the king Charles IV and his son Prince Fernando meant Spain's court was divided into two.

Did you know?

Prince Fernando believed that he was more fit to be the King of Spain than his father, Charles IV, who was an inept ruler. Fernando's ultimate goal was to overthrow his father and rule in his stead.

Napoleon hoped to remove all these problems through a swift invasion and by putting his brother Joseph on the throne. He hoped that by doing so he would reform Spain's military and bolster France's power against Britain.

Spanish Peninsular War

In 1808 Napoleon sent an army of 100,000 troops to conquer Spain and make his brother Joseph the King. As French troops occupied northern Spain, Charles IV was forced to abdicate in favour of his son who was crowned Fernando VII. Napoleon soon forced Fernando VII to abdicate too.

Napoleon installed his brother, Joseph Bonaparte as the King. Joseph Bonaparte was now Joseph I of Spain.

Did you know?

Charles IV and Fernando VII were not only forced to abdicate but became royal prisoners of the French.

Spanish Peninsular War Iberian Revolt

But French betrayal and invasion only served to unite the Spanish population against Joseph I. French armies marched towards Madrid only to be met with fierce opposition from the locals. In May 1808 the Iberian Revolt broke out, marking the beginning of the Spanish Peninsular War.

Resistance from locals during the Spanish Peninsular War gave birth to the term guerrilla warfare.

Guerrilla warfare

A localised, fast-paced fighting tactic conducted by local fighters, popularised by Spanish fighters against the French invasion.

Insurrections and riots in other cities followed suit. The Spanish War of Independence had begun.

Peninsular War Battles

The Spanish revolt against Napoleon proved to be fruitful as they not only managed to hold their own against the famous French Imperial Army for over 5 years but also managed to weaken the French army’s reputation as invincible.

Peninsular War Battles Resistance from Spain and Portugal

The Spaniards fought valiantly. They engaged in many battles and though they were largely won by the French, they still managed to make it as difficult for the invading France to achieve victory. When it came to Portugal, it is important to know that conquering a country does not necessarily mean holding it. The British continued to supply the Portuguese and with them, the Spanish continued resisting the French. The French may have won individual battles, but they continuously failed to turn Spain into their subservient state.

From the very beginning of the war, Britain undermined French ambitions. With the landing of Arthur Wellesley in Portugal in 1808, a series of inconclusive battles were fought between the British and the French until 1812. Though neither side won, Britain was able to prevent France from fully controlling Portugal and taking over its military.

Peninsular War Battles Russia

In 1812 Napoleon invaded Russia. The invasion of Russia devastated Napoleon’s army. Napoleon was forced to withdraw much of the French forces from Spain to bolster his army in Russia. With the united force of British, Portuguese and Spanish troops, the newly allied army defeated the French at the Battle of Vitoria in 1813.

Peninsular War Battles and the End of Napoleon

Following his defeat in Russia, the Coalition believed it was the right time to put down Napoleon once and for all. The Coalition was the alliance between Britain, Austria, Prussia, Russia, and now Spain and Portugal, that formed to defeat Napoleon

So began the War of the Sixth Coalition. The war lasted for just over a year from 1813 to 1814. Napoleon was finally defeated. Later that year he abdicated.

With news of Napoleon's abdication, Arthur Wellesley penetrated south-eastern France with his armies and soon the reign of the Bonaparte in Spain was over. Joseph Bonaparte was forced to abdicate, and in his place, Fernando VII returned to the throne. The Peninsular War was over.

Peninsular War - Key Takeaways

  • France and Spain were initially allies. Officiating this alliance was the Treaty of San Ildefonso of 1796.
  • The alliance between France and Spain became tested after the Battle of Trafalgar in 1805.
  • With the Treaty of Fontainebleau of 1807, France and Portugal allied to divide Spain into three.
  • In 1808 Napoleon's army entered and occupied northern Spain, angering and unifying Spain against the French.
  • The Iberian Revolt broke out in May 1808 across Spain and Portugal.
  • With British aid, the Portuguese and Spanish fought against the French using guerrilla tactics.
  • By 1812 Napoleon began recalling troops from the Iberian peninsula to help the invasion of Russia.
  • The Russian campaign fails and the remaining French troops found it increasingly difficult to hold off the Portuguese, Spanish and British forces.
  • Following his defeat in Russia, the War of the Sixth Coalition began. Napoleon was forced to abdicate from Emperor of the French. His brother Joseph was also forced to abdicate from the Spanish throne where Fernando VII was reinstated as King.


  1. David Chandler, The Campaigns of Napoleon, 1966

Frequently Asked Questions about Peninsular War

The Peninsular War was an armed conflict fought on the Iberian Peninsula from 1808 to 1814. The war took place between French, Portuguese, Spanish and British Forces.

The Peninsular War was won by the allied forces of Portugal, Spain and Britain.

Napoleon believed that he was invincible, thus he thought that weaker states such as Spain or Portugal would not be pose a threat to his power. Furthermore, he never anticipated the Peninsular War to last as long as it did, draining France's money and manpower.

The Peninsular War caused many problems to Napoleon, namely in manpower. Napoleon believed it was possible to suppress the Spanish population into accepting French rule, but this proved futile. What is more Napoleon withdrew some of its troops to go fight in Russia, which also ended in defeat for Napoleon.

The Peninsular War ended with French defeat. Not only that, it ended with the abdication of Napoleon and the subsequent return of Fernando VII in Spain.

Final Peninsular War Quiz


What was the Coalition?

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The Coalition was a grouping of the Kingdoms/Empires of Prussia, Great Britain, Austria, Russia and others, into a single amalgam that sought to defeat Napoleon and France. There were a total of seven Coalition Wars.

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Who was the ruling house of Portugal?

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House of Braganza

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Which French general took Lisbon in 1807?

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Show question


What did the Treaty of Fontainebleau stipulate and when was it signed?

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Treaty of Fontainebleau was signed between France and Spain in 1807. The treaty declared that the ruling House of Braganza was to be exiled from Kingdom and Portugal was to be divided into three independent regions.

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Who was Charles IV's First Minister?

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Manuel Godoy

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Which governor in 1807 initially thought of resisting the incoming French Army?

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Governor of Valença

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Which one of Napoleon's family members became the King of Spain?

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His brother - Joseph I 

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What happened to Charles IV and Fernando VII after they were summoned to Bayonne?

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Charles IV and  Fernando VII were summoned to Bayonne, they were not only forced to abdicate, but they were also imprisoned. The two monarchs were given their respective palaces to live in. 

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Who were the Mamluks?

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Mamluks were freed slave soldiers who were given military duties and served the various Arab dynasties of the Muslim world. Napoleon incorporated the Mamluks into the French Imperial Army in 1804, though their numbers never exceeded more than 2,000.

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Which mutiny caused the dismissal of Godoy as Spain's First Minister? 

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Mutiny of Aranjuez 

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Which War of the Coalition was Napoleon simultaneously fighting in 1809?

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War of the Fifth Coalition

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Why did Napoleon withdraw some of the troops of the Imperial Guard from Spain? 

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By 1812 Napoleon began recalling troops from the Iberian peninsula to invade Russia.

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What happened to the French troops that were left in Spain?

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Following the failure of Napoleon's Russian campaign, the remaining French troops found it increasingly difficult to hold off the Portuguese, Spanish and British forces. They were eventually defeated.

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