Wellington having his battering-train and stores about San Sebastian, which was nearer and more accessible to the enemy than Pampeluna, made his army lean towards that side. His left wing, including the army of siege, was twenty-one thousand, with singularly strong positions of defence; his centre, twenty-four thousand strong, could in two marches unite with the left to cover the siege or fall upon the flanks of an enemy advancing by the high road of Irun; but three days or more were required by those troops to concentrate for the security of the blockade of Pampeluna on the right.
Soult thought no decisive result would attend a direct movement upon San Sebastian, and by his seaboard intercourse he knew that place was not in extremity; but he had no communication with Pampeluna, and feared its fall. Wherefore he resolved rapidly to concentrate on his left by means of the great French roads leading to St. Jean Pied de Port, covering his movement by the Nivelle and Nive rivers, and by the positions of his centre: thus he hoped to gather on Wellington’s right quicker than that general could gather to oppose him, and, compensating by numbers the disadvantage of assailing mountain positions, force a way to Pampeluna.
That fortress succoured, he designed to seize the road of Irurzun, and either fall upon the separated divisions of the centre in detail as they descended from the Great Spine, or operate on the rear of the troops besieging San Sebastian, while a corps of observation, left on the Lower Bidassoa, menaced it in front. The siege of San Sebastian and the blockade of Pampeluna would be thus raised, the French army united in an abundant country, and its communication with Suchet secured.
To mislead Wellington by vexing his right, simultaneously with the construction of the bridges against his left, Soult directed General Paris to march from Jaca, when time suited, by the higher valleys towards Sanguessa, to drive the partizans from that side, and join the left of the army when it should have reached Pampeluna. Clausel was directed to repair the roads in his own front, push the heads of columns towards the Roncesvalles pass, and with a strong detachment menace Hill’s flank by the lateral passes of the Bastan.
On the 20th Reille’s troops on the heights of Sarre and Vera, being cautiously relieved by Villatte, marched towards St. Jean Pied de Port, which they were to reach early on the 22nd; and on that day the two divisions of cavalry and parc of artillery were to concentrate at the same place. D’Erlon, with the centre, was to hold his positions in front of Hill while these great movements were taking place.
Villatte, having fifteen thousand sabres and bayonets, remained in observation on the Bidassoa. If threatened by superior forces he was to retire upon the intrenched camp at Bayonne, halting successively on certain positions. If only a small corps crossed the river, he was to drive it vigorously back; and if the allies retired in consequence of Soult’s operations, he was to relieve San Sebastian and follow them briskly by Tolosa.
Rapidity was of vital importance to the French marshal, but heavy rains swelled the streams and ruined the roads in the deep country between Bayonne and the mountains; the head-quarters which should have arrived at St. Jean Pied de Port on the 20th, were a few miles short of that place the 21st, and Reille’s troops were forced to go round by Bayonne to gain the causeway. The cavalry was also retarded, and the army, men and horses, worn down by severe marches. Two days were thus lost, yet the 24th more than sixty thousand fighting men, including cavalry, national guards, and gens d’armes, with sixty-six pieces of artillery, were assembled to force the passes of Roncesvalles and Maya; the former being in the Great Spine, the latter giving entrance to the Bastan. The main road leading to Roncesvalles was repaired, and three hundred sets of bullocks were provided to drag the guns; the national guards of the frontier on the left, ordered to assemble in the night on the heights of Yropil, were reinforced with regular troops to vex and turn the right of the allies at the foundry of Orbaiceta.
At St. Jean Pied de Port Soult was almost in contact with the allies at the passes of the Roncesvalles, which were also the points of the defence nearest to Pampeluna. He had thirty thousand bayonets, the frontier national guards to aid, and his artillery and cavalry were massed behind his infantry; for here the great road from St. Jean Pied de Port to Pampeluna, the only one fit for cannon, entered the mountains: but to understand his movements a short description of the country is necessary, taking the point of departure from his camp.
Before him was the Val Carlos, formed by two descending shoots from the Great Spine of the Pyrenees. That on his left hand separated this valley from the valley of Orbaiceta; that on his right hand separated it from several conjoint valleys, known as the Alduides and Baygorry, the latter name being given to the lower, the former to the upper parts.
The great road to Pampeluna led up the left hand tongue by the remarkable rocks of Château Pignon, near which narrow branches went off to the village of San Carlos on the right, and to the foundry of Orbaiceta on the left. The main line, after ascending to the summit of the Great Spine, turned to the right and run along the crest until it reached the pass of Ibañeta, where, turning to the left, it led down by the famous Roncesvalles into the valley of Urros.