On the right-hand boundary of Val Carlos, near the rock of Ayrola, Reille’s divisions were concentrated, with orders to ascend that rock at daylight, and march by the crest of the ridge towards a culminant point of the great chain called the Lindouz, which gained, Reille was to push detachments through the passes of Ibañeta and Mendichuri to the villages of Roncesvalles and Espinal. He was, at the same time, to seize the passes of Sahorgain and Urtiaga immediately on his right, and even approach the more distant passes of Renecabal and Bellate, thus closing the issues from the Alduides, and menacing those from the Bastan. [Sidenote: Plan, No. 2.] _Val de Ayra._ _The Alduides._ _Val de Baygorry._ The ridge of Ayrola, at the foot of which Reille’s troops were posted, separates Val Carlos from these valleys which must be designated by the general name of the Alduides for the upper part, and the Val de Baygorry for the lower. The issues from the Alduides over the great chain towards Spain were the passes of Sahorgain and Urtiaga; and there was also a road running from the village of Alduides through the Atalosti pass to Ibañeta a distance of eight miles, by which general Campbell’s brigade communicated with and could join Byng and Morillo. _Bastan._ This district, including the valley of Lerins and the Cinco Villas, is separated from the Alduides and Val de Baygorry by the lofty mountain of La Houssa, on which the national guards of the Val de Baygorry and the Alduides were ordered to assemble on the night of the 24th, and to light fires so as to make it appear a great body was menacing the Bastan by that flank. The Bastan however does not belong to the same geographical system as the other valleys. Instead of opening to the French territory it is entirely enclosed with high mountains, and while the waters of the Val Carlos, the Alduides, and Val de Baygorry run off northward by the Nive, those of the Bastan run off westward by the Bidassoa, from which they are separated by the Mandale, Commissari, La Rhune, Santa Barbara, Ivantelly, Atchiola and other mountains. The entrances to the Bastan with reference to the position of the French army, were by the passes of Vera and Echallar on its right; by the Col de Maya and Arietta passes in the centre; and on the left by the lateral passes of Yspegui, Lorrieta, and Berderez, which lead from the Val de Baygorry and the Alduides. The issues over the principal chain of the Pyrenees in the direct line from the Maya entrances, were the passes of Renecabal and Bellate; the first leading into the valley of Zubiri, the second into the valley of Lanz. There was also the pass of Artesiaga leading into the Val de Zubiri, but it was nearly impracticable, and all the roads through the Bastan were crossed by strong positions dangerous to assail.