It has been already stated that the great spine of the hills, trending westward, run diagonally across the theatre of operations. From this spine huge ridges shot out on either hand, and the communications between the valleys thus formed on both sides of the main chain passed over certain comparatively low places called “_cols_” by the French, and _puertos_ by the Spaniards. The Bastan, the Val Carlos, and the Val de Baygorry the upper part of which is divided into the Alduides and the Val de Ayra, were on the French side of the great chain; on the Spanish side were the valleys of Ahescoa or Orbaiceta, the valley of Iscua or Roncesvalles, the valley of Urros, the Val de Zubiri, and the valley of Lanz, the two latter leading down directly upon Pampeluna which stands within two miles of the junction of their waters. Such being the relative situations of the valleys, the disposition, and force, of the armies, shall now be traced from left to right of the French, and from right to left of the allies. But first it must be observed that the main chain, throwing as it were a shoulder forward from Roncesvalles towards St. Jean Pied de Port, placed the entrance to the Spanish valley of Ahescoa or Orbaiceta, in the power of Soult, who could thus by Yropil turn the extreme right of his adversary with detachments, although not with an army. _Val Carlos._—Two issues led from this valley over the main chain, namely the Ibañeta and Mendichuri passes; and there was also the lateral pass of Atalosti leading into the Alduides, all comprised within a space of two or three miles. The high road from St. Jean Pied de Port to Pampeluna, ascending the left-hand ridge or boundary of Val Carlos, runs along the crest until it joins the superior chain of mountains, and then along the summit of that also until it reaches the pass of Ibañeta, whence it descends to Roncesvalles. Ibañeta may therefore be called the Spanish end of the pass; but it is also a pass in itself, because a narrow road, leading through Arnegui and the village of Val Carlos, ascends directly to Ibañeta and falls into the main road behind it. Clauzel’s three divisions of infantry, all the artillery and the cavalry were formed in two columns in front of St. Jean Pied de Port. The head of one was placed on some heights above Arnegui about two miles from the village of Val Carlos; the head of the other at the Venta de Orrisson, on the main road and within two miles of the remarkable rocks of Chateau Piñon, a little beyond which one narrow way descended on the right to the village of Val Carlos, and another on the left to the foundry of Orbaiceta.