The second battalion of the THIRTY-FIRST regiment shared in the pursuit of the enemy after his defeat at Vittoria, and, when the Marquis of Wellington marched on the 26th of June to intercept the French General Clausel, it remained with the other corps of the second division for the siege of _Pampeluna_. Although the enemy had withdrawn his right and left into France, he maintained his centre in force in the rich valley of _Bastan_, which afforded numerous strong positions, and the troops under Lieut.-General Sir Rowland Hill, having been relieved from the blockade of Pampeluna, advanced to dislodge the French. On the 4th of July, and the three following days, General Gazan was driven from the valley of Bastan by the troops under Lieut.-General Sir Rowland Hill, and the positions abandoned by the enemy were occupied by the British. Major-General Byng’s brigade, of which the THIRTY-FIRST formed part, with some Spanish corps under General Morillo, took possession of the Pass of _Roncesvalles_ on the 7th of July. In this celebrated valley the THIRTY-FIRST remained for a few days. Marshal Soult having arrived at Bayonne on the 13th of July to command, as Lieutenant of the Emperor, the united French army of Spain, amounting to above seventy-eight thousand men, exclusive of garrisons, collected more than sixty thousand of his own left, and advanced on the 25th of July to force the Pass of _Roncesvalles_. The brigade which had been ordered to occupy the Pass, and of which the THIRTY-FIRST formed a part, kept the French in check for several hours, but was obliged to fall back, on perceiving that a strong body had succeeded in turning the position. The THIRTY-FIRST had two privates killed, and three wounded, in the action on the 25th of July. On the 28th and 30th of July, the battalion was engaged in the attack made upon the enemy on the heights in front of _Pampeluna_, and had Captain Girdlestone, Ensign Smith, and Quarter-Master McIntosh, together with thirty-three rank and file, wounded:--two rank and file were killed. Lieut.-Colonel Leith received a clasp, in addition to his former medal, for his conduct on these occasions. The THIRTY-FIRST regiment subsequently received the Royal Authority to bear the word “PYRENEES” on the Regimental Colour and Appointments, to commemorate the services of the second battalion in these several combats, which have been designated the “_Battles of the Pyrenees_.” On the 31st of July, Major-General Byng’s brigade captured a large convoy near _Elizondo_, and made many prisoners. The British troops resumed their position in the Pyrenees, awaiting the capture of St. Sebastian and Pampeluna. St. Sebastian was captured on the 31st of August, and on the 31st of October the French garrison of Pampeluna surrendered prisoners of war.