By calling in the outlying divisions La Serna had, on the 24th October, assembled 10,000 men, in three divisions of infantry under Canterac, Valdés, and Monet, and one of cavalry, which he commanded himself, with ten guns. Sucre had only 7,000 men and two guns.
La Serna manœuvred to cut off Sucre from his base, moving in a semicircle of which the Patriots held the centre. Sucre was thus enabled to concentrate his forces, and choose for himself the field of battle. He retreated on Huamanga, but on the 24th November, at the river Pampas, he found that the enemy by forced marches was there before him. The river lay between them. Three days were spent in manœuvres, after which Sucre crossed the river, but on the 2nd December found the heights of Matará in his front already occupied by the Royalists. Wheeling rapidly to his right, he passed by a gorge towards the valley of Acrocos, but his rearguard under Lara was overtaken in the pass by Valdés. One Columbian battalion was cut to pieces, and two more were dispersed with the loss of a gun on the 3rd December; but the further advance of the Royalists was checked by the main body stationed on the heights beyond. The two armies encamped for the night with the gorge between them.
The next day Sucre gained the valley of Acrocos and offered battle. But La Serna, anxious to cut him off from Jauja, marched round the left flank of the Patriots and again gained their rear, cutting all the bridges and closing the defiles to prevent their retreat. The people of the valleys rose in favour of the Royalists. A Patriot column, advancing from Jauja to join Sucre, was driven back; his sick were killed in the hospitals; and he had lost 600 men in the retreat. For him it was now victory or death.
He drew up his army in the valley of Ayacucho, his flanks resting on the mountain ranges to the east and to the west, while the Royalists occupied the heights in front. Cordoba commanded on the right, Miller in the centre, and La Mar on the left, and a reserve of three battalions was commanded by Lara.
