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.

Immediately on the alarm, Carvajal used his utmost efforts to get his troops into order and to animate and encourage them to exert themselves against the enemy. At this period, Avendano pointed out Carvajal to a musqueteer who was one of the conspirators, and encouraged him to take a steady aim at the lieutenant-general; but owing to the darkness, the shot missed of its intended effect; and only wounded him in one of his thighs. Finding himself wounded, and being satisfied it had been done by one of his own people, Carvajal deemed it prudent to conceal the circumstance for the present; and retired along with Avendano, of whose fidelity he had no suspicion, on purpose to disguise himself in an old brown coat-and a shabby hat, that he might not be conspicuous, after which he returned to animate his men to defend the camp. Avendano again pointed him out to another conspirator, who fired a second time at Carvajal, but entirely missed his aim. In the meantime the assailants frequently called out to know if Carvajal were dead; but receiving no answer, and finding that all the avenues to the camp were bravely defended, Lope de Mendoza drew off his men. In this night engagement about fourteen were slain on both sides, and several wounded. Carvajal got his wound secretly dressed, so that none of his people knew that such a thing had happened.

After the cessation of the engagement, one Placentia deserted from Carvajal's camp, and informed Mendoza that all the baggage belonging to Carvajal and his troops had been left at a place which he described about five or six leagues from Pocona, among which was a large quantity of gold and silver, several horses, and some musquets and powder. On this information, Meodoza set off immediately with his troops for that place, guided by the deserter; and marching diligently all the remainder of the night, he arrived quite unexpectedly at the place where Carvajal had secured his baggage; but as the night was exceedingly dark, above seventy of his men lost their way and fell behind. Yet, with such of his people as had kept up with him, Mendoza took possession of the whole without any resistance. After this, being sensible that he was not in sufficient force to cope with Carvajal, Mendoza resolved to retreat by way of the desert in which Centeno had formerly taken shelter, which he did accordingly with about fifty men, all the rest of his troops having fallen behind during the night, as already mentioned. In the prosecution of this plan of retreat, Mendoza and his people reached a certain river about two leagues and a half from Pocona, where they halted to take some rest and refreshment after the excessive fatigues of the past night. Carvajal was soon apprised of the capture of his baggage and the route which Mendoza had taken, and immediately set off in pursuit with about fifty of his best mounted troops; and, using every possible diligence, he came to the place where Mendoza had halted, about noon of the next day, and immediately attacked the royalists, some of whom were asleep, while others were taking food. Thus unexpectedly assailed, and believing that Carvajal was followed by his whole force, the royalists made a feeble resistance, and very soon took to flight, dispersing themselves in every direction. Lope de Mendoza and Pedro de Heredia, with a good many others, were made prisoners and Carvajal immediately ordered these two chiefs, and six or seven other principal persons among the royalists to be beheaded.