The Battle of Ocaña of 19 November 1809 was a major Spanish defeat that ended any chance of success in the Spanish Junta’s autumn campaign of 1809. The Spanish plan involved two main armies – the Army of the Left operating around Salamanca and the Army of La Mancha. The idea was for the Army of the Left to draw the French reserves away from Madrid, allowing the Army of La Mancha an easy passage to the capital. A third much smaller Army of Estremadura had the job of holding two French corps in place on the Tagus. The Army of the Left had begin the campaign, even winning a battle at Tamames (18 October 1809), and drawing one brigade of infantry away from Madrid.
The Army of La Mancha, under General Carlos Areizaga, began the campaign with 55,000 men. He had begun quickly, advancing fifteen miles per day from 3 to 8 November, reaching La Guardia, only thirty five miles south of Madrid on 8 November. On that day only 10,000 French troops were between him and the city, but Marshal Victor was threatening his left flank from Toledo, and for three days Areizaga held his position at La Guardia.
On 11 November he resumed his advance, only to be held off by a small French force at Ocaña on 12 November. Areizaga then decided to move east, and attempted to cross the Tagus at Villamanrique. By 15 November half of his army was across the river, and his advanced scouts were pushing towards Madrid. The French responded by moving Victor north from Aranjuez. The French intended to defeat the Spanish on the Tajuna River, but Areizaga foiled this plan when he changed his own plans and began a retreat back towards Ocaña.
The French force was officially commanded by King Joseph in person. By now Marshal Soult was serving as his chief-of-staff, with effective command of the army. Observing the Spanish retreat, Soult moved Mortier and Sebastiani towards Aranjuez, hoping to intercept Areizaga, while Victor was sent to cross the Tagus at Villamanrique. As a result Victor would miss the upcoming battle, leaving Soult with 33,500 men – 27,000 infantry, 6,200 infantry and 1,500 artillery and sappers. Despite his losses over the last week, Areizaga still had 46,000 infantry and 5,500 cavalry.
On 18 November the French cavalry crossed the Tagus at Aranjuez, and clashed with the Spanish cavalry around Ocaña. Despite being outnumbered, the French were victorious, but then discovered Spanish infantry in the town and pulled back to join the main French army.
That night Areizaga decided to offer battle, and took up a position on both sides of Ocaña, in a very weak position on a level plain. The Spanish left was covered by a ravine, but the right and centre was unprotected. The French cavalry would be able to operate freely around the Spanish right, and so Areizaga posted all but one of his cavalry brigades to protect that flank.
When Soult and King Joseph discovered the Spanish drawn up in line of battle, a debate broke out on whether the French should attack immediately, or wait for Victor, with Soult apparently in favour of waiting and Joseph determined to attack, on the grounds that the Spanish might leave overnight. If this was so, then for once Joseph was able to impose his will on one of his brother’s marshals.
Soult decided to attack the Spanish right with Sebastiani’s Polish and German divisions. Once the infantry was engaged, the French cavalry would drive off Freire’s Spanish cavalry and then attack the exposed Spanish flank. Girard’s division would support the attack on the Spanish right. Two more infantry brigades (Dessolles and Gazan) would wait for the attack on the right to begin, and then attack the Spanish centre.
This plan worked perfectly, despite a Spanish counterattack. Sebastiani’s divisions made their attack on Lacy’s and Castejon’s divisions on the Spanish right, but were then hit by a counter charge by Lacy, Castejon and Giron’s divisions. Sebastiani’s men fell back, and Mortier was forced to send in his reserves to hold the line. Despite this setback, the French plan was still unfolding. While the Spanish infantry was engaged in their counterattack, the Spanish cavalry was being driven off the battlefield. Once it had fled, most of the French cavalry turned back and charged the Spanish infantry in the flanks. The right wing of the Spanish army collapsed in chaos. Soult then launched his attack against the Spanish centre, which joined the rout. Only Zayas’s division, on the Spanish left, kept its order, fighting a rearguard action for several miles, before eventually breaking at the village of Dos Barrios.
The French captured 14,000 prisoners in the rout, and chased the rest of the army back to the Sierra Morena. Another 4,000 Spanish troops were killed or wounded. Three weeks later only 21,000 infantry and 3,000 cavalry remained with Areizaga’s army. The French suffered surprisingly heavy casualties – nearly 2,000 killed and wounded, most of them in the three divisions that bore the brunt of the early Spanish counterattack. If it had not been for the terrible performance of the Spanish cavalry, the French may have suffered for attacking a larger army.
The victory at Ocaña allowed the French to send reinforcements to the north west to held against the Spanish Army of the Left, although despite catching that army at Alba de Tormes on 28 November they were unable to inflict such heavy losses on it. The failure of the Junta’s autumn campaign forced them to surrender power to the National Cortes, but it also left Andalusia, and the temporary Spanish capital at Seville vulnerable to French attack. Early in 1810 the French invaded Andalusia, and forced the Junta to flee to Cadiz.