The first intention was to turn this position, by advancing Sir Rowland’s corps from Roncesvalles through St. Jean de Pied-de-Port; this movement would turn the sources of the Nive, threaten Soult’s rear, and compel him, it was thought, to abandon his works, and retire beyond Bayonne; but this plan was given up upon full consideration, Soult’s line being so short, and the road behind it so good, that he might have it in his power to fall upon Sir Rowland with a superior force, or to attack Sir John Hope when it would be difficult to reinforce either; or he might retire untouched, and keep his army in a condition to continue active and harass the allies in their winter quarters. Lord Wellington resolved, therefore, to strike at the centre of his position, strong as it was, and at the same time to attack the heights of Ainhoue, which were its immediate support on the left. With this view Sir Rowland had been ordered, as soon as Pamplona should fall, to move leftward, into the valley of Bastan, and the cavalry to close up his rear in readiness for supporting the right of Beresford’s corps at Maya.
The enemy, fully expecting an attack, were always under arms at daybreak, and remained in their redoubts till nightfall; and they improved every day’s delay, which the state of the weather afforded them, in strengthening their works, strong as the labour of three months had already made them. The rain, indeed, continued so many days, and so heavy, that many persons began to fear it would be impossible for them to move; and Lord Wellington, with all his just confidence in himself and in the troops which he commanded, could not but feel how easily human strength and military skill might be baffled by the elements. The weather cleared on the 4th; and on the 7th he met Sir Rowland, Marshal Beresford, and all the chiefs of the right and centre at Urdache, from whence he reconnoitred Ainhoue closely, and pointed out the mode by which that part of the position was to be attacked. The object was to force their centre, and establish the army in rear of their right; and the attack was to be made by columns of divisions, each led by the general officers commanding it, and each forming its own reserve. Sir Rowland directed the movements of the right, consisting of the 2d and 6th divisions, under Sir William Stewart and Sir Henry Clinton, Sir John Hamilton’s Portugueze, and Morillo’s Spanish division, Colonel Grant’s brigade of cavalry, a brigade of Portugueze artillery under Lieutenant-Colonel Tulloh, and three mountain guns under Lieutenant Robe. Marshal Beresford directed the right of the centre, with the 3rd, 7th, and 4th divisions, under Major-General Colville, Camp-Marshal Le Cor and Sir Lowry Cole. Giron was to act on his immediate left with the Andalusian army of reserve. Baron Alten’s light division, with three mountain guns, and Longa’s corps, was to attack La Petite Rhune; Sir Stapleton Cotton to follow the movement of the centre, with General Alten’s brigade of cavalry, and three brigades of British artillery. Freyre, with the Galician army, was to move from the heights of Mandale toward Ascain, prevent the enemy from detaching troops from thence to the support of others, and take advantage of any movement which they might make from their right toward their centre; and Sir John Hope was to act along the remainder of their line to the sea.