By this time, Mortier's and Wellesley's cavalry were already bickering near Navalmoral only about 30 miles (48.3 km) west of Oropesa.
On 3 August, the French horsemen captured a Spanish courier carrying a message from Wellesley to General William Erksine at Lisbon in which Soult's forces were estimated at only 12,000 men.
Soult saw that Wellesley was marching right into his hands.
Luckily for the Allies, Spanish guerillas caught a French agent near Ávila and delivered his message to Cuesta on the 3rd.
It was a note from Soult to Joseph, informing the king that he was advancing with over 30,000 soldiers.
Cuesta quickly passed along the message to Wellesley.

Alerted to imminent danger, the British commander instantly ordered a retreat across the bridge at Arzobispo.
For his part, Cuesta immediately led his army in retreat from Talavera to Oropesa, abandoning the British hospitals.
With only about 40 wagons and carts available, 1,500 badly wounded men were left behind.
The remainder were told to make their way as best they could.
Eventually, 2,000 hobbled into the British lines.
Another 500 either died en route or were captured by the French.
The ones who were made prisoner by the French were well cared for.
Cuesta could have crossed the Tagus at Talavera and retreated on the south bank.
However, the roads on that side pass through the Sierra de Guadalupe and were so bad that the Spanish army would have had to abandon its artillery and wagon train.
Instead, Cuesta took the risk of marching on the north bank, where the French were known to be at large.

By the evening of 4 August, Wellesley's army was safe on the south bank of the Tagus at Arzobispo.
But Cuesta stubbornly refused to retreat.
When Mortier's vanguard appeared before him, the Spanish general lashed out at it and drove it back.
Believing that he was facing both Cuesta and Wellesley, Mortier became cautious and called for assistance from Soult.
During the entire day of the 5th, Cuesta foolishly offered battle with the bridge of Arzobispo at his back, yet Mortier held back.
By 6 August when both Soult and Mortier were massed for battle, they found their quarry had withdrawn across the Tagus.
As it happened, this was the only opportunity that the French had for inflicting great damage on the Spanish army.
As historian Charles Oman wrote, "Soult's best chance was gone before he was even aware of it."

Worried about his supply line to Portugal, Wellesley ordered Craufurd to march west with his own brigade and General Rufane Donkin's brigade to cover the Almaraz crossing.
On 6 August, the last day of the march, the troops marched 15 hours on a meal of boiled wheat and dried peas without salt or meat.
One participant later recalled that the straggling was the worst he ever saw in the entire war.
Craufurd reached Almaraz with 4,000 British troops and joined 1,500 Spaniards under Del Reino.
Ney's French troops arrived on the north bank the next day.
After retreating from the Puerto de Baños, Del Reino crossed to the south bank of the Tagus at Almaraz and dismantled the pontoon bridge on the 2nd.
After a difficult march over bad roads, two divisions of Wellesley's army reached Deleitosa on 7 August, within supporting distance of Almaraz.
Another British division was holding Mesas de Ibor.
That day, the head of Cuesta's column was approaching Mesas de Ibor where there was an immensely strong defensive position.
The rest of the Spanish army struggled slowly over the hills.
To cover the movement, the Spanish divisions of Bassecourt and Lieutenant General Alburquerque formed a rear guard at the Arzobispo bridge.
Meanwhile, Victor's I Corps occupied Talavera on the 6th, but it remained to the east of the theater of action.
By this time, Mortier's and Wellesley's cavalry were already bickering near Navalmoral only about 30 miles (48.3 km) west of Oropesa. On 3 August, the French horsemen captured a Spanish courier carrying a message from Wellesley to General William Erksine at Lisbon in which Soult's forces were estimated at only 12,000 men. Soult saw that Wellesley was marching right into his hands. Luckily for the Allies, Spanish guerillas caught a French agent near Ávila and delivered his message to Cuesta on the 3rd. It was a note from Soult to Joseph, informing the king that he was advancing with over 30,000 soldiers. Cuesta quickly passed along the message to Wellesley.
Alerted to imminent danger, the British commander instantly ordered a retreat across the bridge at Arzobispo. For his part, Cuesta immediately led his army in retreat from Talavera to Oropesa, abandoning the British hospitals. With only about 40 wagons and carts available, 1,500 badly wounded men were left behind. The remainder were told to make their way as best they could. Eventually, 2,000 hobbled into the British lines. Another 500 either died en route or were captured by the French. The ones who were made prisoner by the French were well cared for. Cuesta could have crossed the Tagus at Talavera and retreated on the south bank. However, the roads on that side pass through the Sierra de Guadalupe and were so bad that the Spanish army would have had to abandon its artillery and wagon train. Instead, Cuesta took the risk of marching on the north bank, where the French were known to be at large.
By the evening of 4 August, Wellesley's army was safe on the south bank of the Tagus at Arzobispo. But Cuesta stubbornly refused to retreat. When Mortier's vanguard appeared before him, the Spanish general lashed out at it and drove it back. Believing that he was facing both Cuesta and Wellesley, Mortier became cautious and called for assistance from Soult. During the entire day of the 5th, Cuesta foolishly offered battle with the bridge of Arzobispo at his back, yet Mortier held back. By 6 August when both Soult and Mortier were massed for battle, they found their quarry had withdrawn across the Tagus. As it happened, this was the only opportunity that the French had for inflicting great damage on the Spanish army. As historian Charles Oman wrote, "Soult's best chance was gone before he was even aware of it."
Worried about his supply line to Portugal, Wellesley ordered Craufurd to march west with his own brigade and General Rufane Donkin's brigade to cover the Almaraz crossing. On 6 August, the last day of the march, the troops marched 15 hours on a meal of boiled wheat and dried peas without salt or meat. One participant later recalled that the straggling was the worst he ever saw in the entire war. Craufurd reached Almaraz with 4,000 British troops and joined 1,500 Spaniards under Del Reino. Ney's French troops arrived on the north bank the next day. After retreating from the Puerto de Baños, Del Reino crossed to the south bank of the Tagus at Almaraz and dismantled the pontoon bridge on the 2nd. After a difficult march over bad roads, two divisions of Wellesley's army reached Deleitosa on 7 August, within supporting distance of Almaraz. Another British division was holding Mesas de Ibor. That day, the head of Cuesta's column was approaching Mesas de Ibor where there was an immensely strong defensive position. The rest of the Spanish army struggled slowly over the hills. To cover the movement, the Spanish divisions of Bassecourt and Lieutenant General Alburquerque formed a rear guard at the Arzobispo bridge. Meanwhile, Victor's I Corps occupied Talavera on the 6th, but it remained to the east of the theater of action.
Battle of Arzobispo