His confidence and moral authority having been much boosted by holding the Lines of Torres Vedras, the spring of 1811 found Wellington intending to move over to the offensive, for which policy he had received de facto authorisation from his political masters in London, where talks of major reductions in the size of the army employed in Portugal had been replaced by promises of major reinforcements.

Supply difficulties, sickness amongst the troops and want of siege artillery ensured that in the short term no great strokes of strategy could be envisaged, but it was hoped that Almeida, Ciudad Rodrigo and Badajoz might be all recaptured, thereby opening the way for lightning strikes on such targets as Salamanca or Seville.

Having first secured Portugal, Wellington then set about re-taking the fortified frontier cities of Almeida, Badajoz, and Ciudad Rodrigo.

Whilst Wellington besieged Almeida, Masséna reformed his battered army and marched to relieve the French garrison in the city.

Wellington chose to check the relief attempt at the small village of Fuentes de Oñoro, leaving his line of retreat exposed in order to cover all routes to Almeida.

Louis Henri Loison's VI Corps had three divisions, led by Jean Gabriel Marchand, Julien Augustin Joseph Mermet, and Claude François Ferey.

Jean Reynier's II Corps hovered off to the northeast, threatening Almeida with its two divisions under Pierre Hugues Victoire Merle and Étienne Heudelet de Bierre.

At first, the British–Portuguese were driven back under immense pressure, but a charge that included men of the 71st Highland Light Infantry reclaimed the streets and buildings lost earlier in the day.

Masséna launched a heavy attack on the weak British–Portuguese flank, led by Montbrun's dragoons and supported by the infantry divisions of Marchand, Mermet, and Solignac.

The young Oudinot hastily set off and Masséna was impatiently checking his watch, pressed to commit this cavalry to what he believed was a decisive action of the battle.

In a staggering display of treachery, Bessières was absent from the field of battle, needlessly inspecting a series of ditches where the French army had passed a few days before.

One occurred when a British 14th Light Dragoon squadron pressed home a frontal attack on a French artillery battery and was mauled.

The village, filled with low stone walls, provided excellent cover for the British line infantry and skirmishers, while the French were severely restricted in the little narrow streets.

At first, the French had some success, wiping out two companies of the 79th Foot and wounding the regiment's commander, Lieutenant-Colonel Philips Cameron, who died some days later.

[10] Wellington had repelled Napoleon's Army of Portugal, inflicting a great number of casualties, and was able to continue his blockade of Almeida.

"[13] Russian historian Oleg Sokolov noted that Wellington had committed a serious strategic error by following the French into northern Portugal, and that this decision could have had grievous consequences for the British–Portuguese.

Sokolov adds that, despite the various setbacks that he encountered before and during the battle, Masséna was still able to check Wellington's position at Fuentes de Oñoro.

[15] The confusion came about because the Hanoverian Legion wore red coats, and in the smoke and heat of battle the finer details of uniforms that might have distinguished them from British line infantry were easily overlooked.

"[16] The battle is included in the list of French victories on the Arc de Triomphe as FUENTE D'OŨORO, despite being a tactical draw and strategic defeat.