After a considerable delay, during which daily skirmishes passed between the adverse parties, Giron resolved to make a night attack upon the camp of the royalists, confiding in the prediction of some wise old woman, that he was to gain the victory at that place. For this purpose he marched out from his natural fortress at the head of eight hundred foot, six hundred of whom were musqueteers, and the rest pikemen, with only about thirty horse. His negro soldiers, who were about two hundred and fifty in number, joined with about seventy Spaniards, were ordered to assail the front of the royal camp, while Giron with the main body was to attack the rear. Fortunately the judges had got notice of this intended assault from two rebel deserters, so that the whole royal army was drawn out in order of battle on the plain before the rebels got up to the attack. The negro detachment arrived at the royal camp sometime before Giron, and, finding no resistance, they broke in and killed a great number of the Indian followers, and many horses and mules, together with five or six Spanish soldiers who had deserted the ranks and hidden themselves in the camp. On arriving at the camp, Giron fired a whole volley into the fortifications without receiving any return; but was astonished when the royal army began to play upon the flank of his army from an unexpected quarter, with all their musquets and artillery. Giron, being thus disappointed in his expectations of taking the enemy by surprise, and finding their whole army drawn up to receive him, lost heart and retreated back to his strong camp in the best order he could. But on this occasion, two hundred of his men, who had formerly served under Alvarado, and had been constrained to enter into his service after the battle of Chuquinca, threw down their arms and revolted to the royalists.