In the course of their expedition they asserted that they had penetrated six hundred leagues to the eastwards of La Plata, through a champaign country of very easy access, and tolerably abounding in provisions and water. Bermudez added, that within a very few days they had learnt, from some Indians who occasionally traded into the province of Las Charcas, of the revolt which had taken place in Peru, but had been unable to procure information respecting the causes of this insurrection or as to who were chiefly engaged in it; for which reason he had been sent on before to inquire into these circumstances, and had received orders from the captains and other principal persons in the expedition, to offer their services to the party that acted for the royal interests, in which cause they might be of material importance, as they had a considerable number of excellent horses and plenty of arms. After the conclusion of this narrative, Mendoza gave Bermudez an account of all the late events in Peru; on which, in, virtue of the commission with which he had been entrusted, Bermudez promised in the name of all his companions to march against the lieutenant-general.
Lope Mendoza and Bermudez went after this to meet the troops which were returning from the Rio Plata, which were at no great distance. When they were informed of the situation of affairs in Peru, they received Lope with every demonstration of respect, and confirmed the offers of assistance which Bermudez had already made in their name, declaring their resolution to devote themselves heartily to the service of the king. Lope de Mendoza gave them hearty commendations for their loyalty, and represented to them how honourable and praiseworthy it was to exert their utmost endeavours in the cause of their lawful sovereign; assuring them that they might all depend upon being amply provided for, when the country was restored to obedience. Lope de Mendoza was unanimously received as their chief, and conducted them to the village of Pocona, about forty leagues to the north-east of La Plata; whence he sent some confidential persons to certain secret places where he and Centeno had hidden above a thousand marks of silver under ground. On recovering this treasure, he proposed to divide it among those persons who had so nobly offered to follow his orders; but most of them refused his preferred bounty, either because they were already sufficiently rich, or because hitherto the soldiers who had been engaged in the wars of Peru had been unused to any regular pay, and only accepted money to answer their immediate wants, and to provide themselves with horses and arms. Even the lowest soldier, in those days expected, when the enterprizes of their leaders succeeded, to be rewarded for his services in repartitions or advantageous establishments in the country, by which they flattered themselves to acquire riches, so great was the reputation of the richness of Peru. By means of these men from the Rio Plata, Lope Mendoza found himself unexpectedly at the head of an hundred and fifty well mounted cavalry; all excellently armed and equipped for service. It was a great misfortune to the royal cause, that Centeno was now concealed, instead of having retreated into the interior along with Mendoza as he had done formerly; as if he had now been at the head of the royalists, with this important reinforcement, affairs might have taken a better turn than they actually did.
While Carvajal was on his way from Arequipa for the city of La Plata, he received intelligence of the success of Gonzalo Pizarro at Quito, and that all Peru was entirely reduced under his command. He resolved therefore to repair to La Plata, as formerly mentioned, intending to regulate the affairs of the province of Las Charcas, and to collect treasure. On his arrival however at Paria on his way to La Plata he received intelligence of the arrival of the troops from the Rio Plata and of their junction with Lope Mendoza. Being informed at the same time that these unexpected opponents were by no means united among themselves, and that they marched very carelessly in separate and unconnected detachments, most of which refused to acknowledge any one as their commander, he determined to set out against them with the utmost diligence, that he might fall upon them in their present divided state. Being rejoined by the detachment which had pursued Lope Mendoza, and having put his men in order for a fresh expedition, Carvajal set out from La Plata and marched towards the enemy with the utmost possible speed, encouraging his troops by the assurance of an easy and bloodless victory, even asserting that he had received letters from the principal officers among the enemy in which they offered their services to him, so that they would only have the trouble of marching, without any danger of fighting.
During this march Carvajal was joined by thirty men in addition to his former force, so that he was now at the head of two hundred and fifty men. At length he came in sight of Pocona, which is eighty leagues from Paria, about four o'clock of an afternoon, and made his appearance in good order, on the top of a rising ground within view of Lope de Mendoza, who was then making a distribution of money among such of his new companions as were willing to accept his bounty: Mendoza had already got some intimation of the approach of Carvajal; and as his own force consisted entirely of cavalry, most of whom were persons of some consideration, remarkably well mounted and armed, he drew up his men in good order in a plain at some distance from the village, in which he left the baggage and his money; saying, that he trusted through their bravery to be soon able to recover both, and even to increase their store by that belonging to their enemies. Carvajal immediately descended from the hill he had first taken possession of, and took post in the place which Mendoza had just quitted, which was an inclosare of considerable extent surrounded with walls, in which there were openings in several places. Carvajal chose this as a convenient post for the night, in which the enemy would not be able to attack with their cavalry. On learning that Lope de Mendoza and his men had left their baggage in the town of Pocona, the troops of Carvajal immediately quitted their ranks to go in search of plunder, insomuch that Carvajal was left in his camp with hardly eight men. If Mendoza had availed himself of this opportunity to attack Carvajal, he might have gained an easy victory, and might have boasted of having left his baggage exposed to plunder as a stratagem of war, which on similar occasions had often been the cause of signal victories. On purpose to recall his troops to their duty, Carvajal ordered a false alarm to be sounded, which occasioned the return of the greater part of his men; but so strong was their avidity for spoil that most part of the night was spent before they all returned to the camp.
At this time there was a secret conspiracy entered into by many of Carvajal's followers, with the intention of putting him to death out of revenge for his harsh and tyrannical conduct towards them, and one Pedro de Avendano, his secretary, in whom he reposed entire confidence was the principal ringleader of the conspirators. To facilitate the execution of this enterprize, Avendano, sent a message by a clever fellow of an Indian to give Mendoza notice of the intentions of the conspirators, and to request he would make an attack upon Carvajal's camp in the course of the night, in the confusion attendant upon which he and the other conspirators might have an opportunity of executing their intended plot. Mendoza had previously determined upon withdrawing about four or five leagues from Pocona, to a level plain in which his cavalry would be able to act with much advantage. But on receiving the message of Avendano, he ordered his men to hold themselves in readiness to attack the camp of Carvajal at the going down of the moon, preferring the obscurity of night in order to avoid the danger of the more numerous firearms of the enemy. At that time he advanced in good order towards the enemy, sending some scouts in advance, who made prisoner of one of Carvajal's soldiers. After interrogating this man, they advanced to the openings of the wall which surrounded the camp, which they found guarded by some musqueteers and pikemen. Mendoza made a brisk attack, but was bravely resisted by the enemy, and so great was the confusion and noise that it was impossible to enter upon any parley, as no one could be heard by reason of the continual firing and the shouts of the combatants.