| Date | 18 October 1807 – 17 April 1814 |
| Location | Iberian Peninsula (Spain, Portugal, southern France) |
| Caused by | French invasion of Portugal under the Treaty of Fontainebleau (1807); forced abdication of the Spanish royal family at Bayonne (1808) |
| Resulted in | Expulsion of French forces from the Iberian Peninsula; restoration of Bourbon monarchy in Spain; Portuguese sovereignty preserved; broader Napoleonic strategic overextension |
| Parties | France · Kingdom of Spain (Josefino) · United Kingdom · Kingdom of Spain (Patriot) · Kingdom of Portugal · Spanish guerrilla forces |
| Lead figures | Napoleon Bonaparte, Arthur Wellesley, Duke of Wellington, Joseph Bonaparte, Marshal Nicolas Soult, Marshal Auguste Marmont, General Andoche Junot, Sir John Moore |
The Peninsular War was a military conflict fought from 1807 to 1814 on the Iberian Peninsula, principally involving France, Spain, Portugal, and Great Britain. The war began when Napoleon Bonaparte ordered French forces into the peninsula under the pretence of reinforcing the Franco-Spanish occupation of Portugal, a campaign that rapidly expanded into a broader struggle for control of Spain itself. The conflict resulted in the expulsion of French forces from the peninsula and is widely regarded as a decisive turning point in the Napoleonic Wars.
By 1807, Napoleon Bonaparte had extended French influence across much of continental Europe. Portugal, as Britain's oldest treaty ally, continued to trade openly with the United Kingdom in defiance of Napoleon's Continental System — a blockade intended to strangle British commerce. In October 1807, France and Spain concluded the Treaty of Fontainebleau, which partitioned Portugal between the two powers and authorised French troops to march through Spanish territory.
French forces under General Andoche Junot crossed the Pyrenees in October 1807 and entered Lisbon on 30 November, hours after the Portuguese royal family had sailed for Brazil under British naval escort. This displacement of the Braganza dynasty, reported in dispatches now held at the Arquivo Histórico Militar in Lisbon, provoked widespread resistance and established the war's central political dynamic: the defense of legitimate monarchy against Napoleonic installation.
The situation in Spain deteriorated sharply in the spring of 1808 when Napoleon summoned the Spanish royal family to Bayonne and compelled King Charles IV and Crown Prince Ferdinand VII to abdicate, placing his brother Joseph Bonaparte on the Spanish throne. This act, which the Spanish population rejected with near-unanimous hostility, triggered the popular uprising known as the Dos de Mayo, beginning on 2 May 1808 in Madrid.
### May 1808
The Dos de Mayo uprising was suppressed with considerable violence by French Marshal Joachim Murat's forces in Madrid. Executions of suspected rebels on 3 May 1808 — later documented in Francisco Goya's painting *The Third of May 1808* — accelerated the formation of provincial juntas across Spain. By the end of May, organised resistance had coalesced in Andalusia, Asturias, Galicia, and Valencia, each junta independently declaring war on France.
### June–July 1808
British military assistance was formally requested by the Asturian junta in June 1808. A British expeditionary force of approximately 13,500 men under Lieutenant-General Sir Arthur Wellesley landed in Portugal on 1 August 1808. Within weeks, Wellesley's forces defeated French General Henri Delaborde at the Battle of Roliça on 17 August and the larger engagement at Vimeiro on 21 August. The subsequent Convention of Sintra, concluded on 30 August 1808, controversially permitted the evacuation of Junot's army from Portugal aboard British ships — an arrangement that provoked public outrage in Britain and led to a formal inquiry, the proceedings of which are recorded in the *Report of the Board of General Officers* (1809).
### 1809–1812
The war entered its most attritional phase following the death of Sir John Moore at the Battle of Corunna on 16 January 1809, which necessitated a temporary British withdrawal. Wellesley returned to Portugal in April 1809, secured the Douro crossing at Oporto in May, and thereafter conducted a sustained campaign of advance and consolidation through western Spain. The Lines of Torres Vedras — a system of fortified defensive positions constructed in secret across forty miles of Portuguese terrain north of Lisbon — were completed by October 1809 under the direction of Lieutenant-Colonel Richard Fletcher of the Royal Engineers, and held throughout the French advance of 1810–1811.
The Battle of Salamanca on 22 July 1812 marked the strategic turning point of the campaign. Wellesley, by then created Viscount Wellington, shattered Marshal Auguste Marmont's Army of Portugal in under forty minutes of decisive action, opening the road to Madrid. Wellington entered Madrid on 12 August 1812 to public celebration.
### 1813–1814
Following a temporary setback at Burgos in the autumn of 1812 and a further withdrawal to Portugal, Wellington resumed the offensive in the spring of 1813. The Battle of Vitoria on 21 June 1813 effectively ended French military control of Spain. King Joseph Bonaparte fled the country, leaving behind his personal baggage train — subsequently divided among Wellington's troops — and the Army of Spain disintegrated as an organised force. Continued operations in the Pyrenees and the Battle of Toulouse on 10 April 1814 concluded the campaign, four days before Napoleon's abdication at Fontainebleau.
The conclusion of the war was received with considerable ceremony in Britain, Spain, and Portugal. Wellington was elevated to the rank of Field Marshal in June 1813 following Vitoria, having previously been created Earl, Marquess, and Duke of Wellington in successive years. The Spanish Cortes, which had convened in Cádiz under French pressure throughout the conflict and promulgated the liberal Constitution of 1812, found its authority contested upon the return of Ferdinand VII, who dissolved the Cortes in May 1814 and reinstated absolute monarchy — an outcome not anticipated by British strategists.
In France, the campaign was absorbed into a broader narrative of Napoleonic reversal. Marshal Soult, who had commanded French forces in the final peninsular operations, was nonetheless promoted and continued to serve in subsequent administrations. Parliamentary accounts of the war's cost, including the *Report of the Commissary-General's Office* (1815), placed British expenditure in the peninsula at approximately £45 million over six years of active campaigning.
The Peninsular War is chiefly remembered in British military history as the campaign that established the Duke of Wellington's reputation as a commander and confirmed the strategic utility of combined Anglo-Iberian operations. It also demonstrated the vulnerability of extended French supply lines to sustained partisan resistance — a lesson that contributed directly to Napoleon's subsequent miscalculations in Russia in 1812. The Spanish irregular fighters, operating in coordinated regional bands, provided the English language with the word *guerrilla*, derived from the Spanish diminutive of *guerra* (war), meaning "little war."
The conflict is also considered foundational to the development of modern Spanish national identity, having mobilised popular resistance across regional, class, and ideological lines to a degree not previously achieved in Spanish political history. The Cádiz Constitution of 1812, though swiftly abrogated, became a touchstone for subsequent liberal movements throughout the Spanish-speaking world.
Military historians at the Army Historical Branch, whose records are held jointly with the [Royal Signals Museum](/wiki/royal-signals-museum), have catalogued over 1,200 engagements of varying scale during the six-year campaign — a figure that underscores the war's character as a conflict fought not in a handful of decisive battles but across a continuous patchwork of sieges, skirmishes, and partisan actions.
The Peninsular War has sustained a substantial popular cultural presence, most prominently through Bernard Cornwell's *Sharpe* series of novels (1981–2006), in which the fictional rifleman Richard Sharpe participates in major engagements from Talavera to Waterloo. The novels, which draw heavily on regimental histories and contemporary diaries held at the [London Metropolitan Archives](/wiki/london-metropolitan-archives) and the National Army Museum, have been credited with generating renewed public interest in the period in the United Kingdom.
Francisco Goya's *Disasters of War* (1810–1820), a series of eighty-two prints documenting atrocities committed by both French and Spanish forces, remains the most cited artistic record of the conflict. Goya, who was living in Madrid during the French occupation, produced the series privately and did not publish it during his lifetime; the prints were first published posthumously in 1863 by the Real Academia de Bellas Artes de San Fernando. The series is held in collections at the Prado Museum and the British Museum, among others.