Napoleon's failure in Russia considerably altered the aspect of affairs in the Peninsula, since he once again drafted thousands of his best soldiers and officers to stiffen the new levies with which he strove to oppose his enemies in Germany. Notwithstanding this, he had still 230,000 men in the Peninsula, of which 120,000 were barring the northern route from Spain to France, with reserves at Bayonne. It was at this juncture, in May 1813, that Wellington ordered Graham to advance from Portugal through Tras os Montes to the Esla River with an army of 40,000 men, so as to turn the line of the Douro, whilst he himself, with 30,000, moved direct on the Tormes, with the object of forcing a passage at Salamanca, crossing the Douro, and joining hands with Graham. The Galicians under CastaÑos were now to meet him, and the three forces, amounting to 90,000 men, were then to advance on a broad front and force the French back on the Pyrenees. "A grand design and grandly executed" are the words of Napier.

King Joseph made desperate efforts to assemble his scattered forces, and after various changes of plans, fell back to the Ebro and took up a position behind the Zadorra River, covering Vitoria, where an immense amount of war material and treasure was collected.

Wellington, pushing forward without intermission, attacked the French on 21st June at Vitoria, and inflicted a most crushing defeat on them, capturing all their guns, stores, and treasure. The French army retreated to the shelter of the walls of Pamplona, King Joseph fleeing to France. The victorious advance of the allies had placed Foy and Clausel, on either flank, in danger of being cut off. The former, although roughly handled by Graham, made good his retreat to the Bidasoa; the latter, pursued by Wellington himself, retreated to Zaragoza, and after destroying his guns and baggage, escaped with his force into France.

San Sebastian was now besieged by the allies, and on 24th July, an attempt was made to storm it, but was repulsed with heavy loss, and the siege perforce turned into a blockade. Soult had meanwhile been appointed to command the "Army of Spain," as it was now styled, King Joseph having been wise enough to voluntarily resign.

Now commenced the fighting which, under the name of "Pyrenees," is so well known. Combat succeeded combat with unceasing rapidity, commencing with that of Roncesvalles on 25th July. In nine days, in August, ten serious actions were fought, the allies losing some 7300 men, and the French about double that number.

The siege of San Sebastian was now resumed, and on 31st August it was stormed, but at the expense of appalling losses to those of the allies engaged. Meanwhile, Soult fought a battle on the Bidasoa with the covering force at San Marcial, and another at Vera.

After the fall of San Sebastian, there was a lull in the fighting for some weeks, and it was not till 6th October that the allies effected the passage of the Bidasoa, and on the following day fought the second combat of Vera, in which the Rifles took a leading part and lost over 200 officers and men, killed and wounded.

Soult now entrenched himself strongly on the line of the Nivelle, but on 10th November, the battle of the Nivelle was fought and Soult retreated behind the Nive. Wellington having been compelled to divide his wings by this river, Soult projected an attack on one of them with his whole force, the entrenched camp of Bayonne on the Nive assisting him in this enterprise. The battles and combats which ensued are commonly known as the battles in front of Bayonne, that of the 10th December being distinguished as the battle of the Nive, although they all took place in the same theatre of operations.

In the five days' fighting before Bayonne (9th to 13th December) the French lost 6000 men and the allies about 5000.

After some minor operations, hostilities ceased for a brief period on the 18th December, only to be renewed with redoubled energy within less than two months.