At daybreak on the 21st of June, 1813, the weather being rainy with some mist, the troops moved from their quarters on the Bayas, passed in columns over the bridges in front, and slowly approached the Zadora. About ten o'clock, Hill seized the village of Puebla, and commenced the passage of the defile, while one of the Portuguese battalions scaled the heights above. Here the French met them, and a fierce fight ensued; the French were reinforced on their side, while the 71st Regiment and a battalion of light infantry joined the Portuguese.

Villette's division was sent from the French center to join the fray, while Hill sent up reinforcements. While the fight on the heights still raged, the troops in the defile made their way through, and, driving the French back, won the village of Subijano de Alava, in front of the French main position.

Meanwhile, far to the left, Graham came into action with Reille's division at Gamara Mayor. The French here, knowing the vital importance of the position, fought desperately, and the village of Gamara was taken and retaken several times, but no effort upon the part of the allies sufficed to carry either the bridge at this place or that by which the main road crossed the river higher up. A force, however, was pushed still farther to the left, and there took up a position on the road at Durana, drove back a Franco-Spanish force which occupied it, and thus effectively cut the main line of retreat to France for Joseph's army. The main force under Wellington himself was later in coming into action, the various columns being delayed by the difficulties of making their way through the defiles.

While waiting, however, for the third and seventh divisions, which were the last to arrive, a peasant informed Wellington that the bridge of Tres Puentes was unbroken and unguarded. Kempt's brigade of the light division were immediately ordered to cross, and, being concealed by the inequalities of the ground, they reached it and passed over unobserved, taking their place under shelter of a crest within a few hundred yards of the French main line of battle, and actually in rear of his advanced posts.

Some French cavalry now advanced, but no attack was made upon this isolated body of British troops, for the French were virtually without a commander.

Joseph, finding his flank menaced by the movements of Graham and Hill, now ordered the army to fall back to a crest two miles in the rear, but at this moment the third and seventh divisions advanced at a run towards the bridge of Mendoza, the French artillery opened upon them, the British guns replied, a heavy musketry fire broke out on both sides, and the battle commenced in earnest. Now the advantage gained by the passage of Kempt's brigade became manifest, for the riflemen of his division advanced and took the French advanced cavalry and artillery in flank. These, thus unexpectedly attacked, fell back hastily, and a brigade of the third division took advantage of the moment and crossed the bridge of Mendoza. The other brigade forded the river a little higher up, the seventh division and Vandeleur's brigade of the light division followed, Hill pushed the enemy farther back, and the fourth division crossed by the bridge of Nanclares; other troops forded the river, and the battle became general all along the line.

Seeing that the hill in front of Arinez was nearly denuded of troops by the withdrawal of Villette's division earlier in the day to oppose Hill, Wellington launched Picton with the third division and Kempt's brigade against it, and the French, thus attacked with great strength and fury, and dispirited by the order to retreat, began to fall back. Fifty pieces of artillery and a cloud of skirmishers covered the movement, and the British guns answering, the whole basin became filled with a heavy smoke, under cover of which the French retired to the heights in front of Gomecha, upon which their reserves were posted. Picton and Kempt carried the village of Arinez with the bayonet, Vandeleur captured the village of Margarita, and the 87th Regiment won that of Hermandad.

This advance turned the flank of the French troops near Subijana de Alava, and of those on the Puebla mountain, and both fell back in disorder for two miles, until they made a junction with the main body of their army. Still the British troops pressed forward, the French again fell back, and for six miles a running fight of musketry and artillery was kept up, the ground being very broken, and preventing the concerted action of large bodies of troops. At six o'clock in the afternoon the French stood at bay on the last heights before Vittoria, upon which stood the villages of Ali and Armentia. Behind them was the plain upon which the city stood, and beyond the city thousands of carriages, animals, and non-combatants, women, and children, were crowded together in the extremity of terror as the British shots rang menacingly over their heads.

The French here defended themselves desperately, and for a while the allied advance was checked by the terrible fire of shot and shell. Then the fourth division with a rush carried a hill on the left, and the French again commenced their retreat. Joseph, finding the great road absolutely blocked up, gave orders for a retreat by the road to Salvatierra, and the army, leaving the town of Vittoria on its left, moved off in a compact mass towards the indicated road. This, however, like the other, was choked with carriages. It led through a swamp, and had deep ditches on each side; the artillery, therefore, had to cut their traces and leave their guns behind them, the infantry and cavalry thrust aside the encumbrances and continued their march. Reille, who had defended the upper bridges nobly until the last moment, now came up, and his division acting as a rear guard, covered the retreat, and the French retired with little further loss.

They had lost the battle solely and entirely from the utter incapacity of their general, for their loss had been but little greater than that of the allies, and they fell back in perfect order and full of fighting. The French loss, including prisoners, was not more than 6000, and that of the allies exceeded 5000. The French loss, however, in material was enormous. They carried off two guns only, and 143 fell into the hands of the British. They lost all their parks of ammunition, all their baggage, all their stores, all their treasures, all their booty. Last of all, they lost Spain.