Some time in the year 1537, Almagro received a considerable reinforcement from Peru under the command of Juan de Rada; who likewise brought him letters patent from the king of Spain, by which he was appointed governor of 200 leagues of territory to the southward of the government which had been granted to Francisco Pizarro. By the same conveyance Almagro received letters from his friends in Peru, urging him to return to that country and to take possession of Cuzco, which they asserted was within the limits of the jurisdiction confided to him by his patent. But, as he entertained very sanguine ideas of the value of the conquest in which he was now engaged, he pursued his march towards the south, and passed the fatal _Cachapoal_ or _Rapel_, regardless of the remonstrances of his Peruvian allies, who urged him to refrain from attempting to invade the country of the valiant Promaucians[63]. At the first appearance of the Spaniards, these brave Indians were astonished and terrified by the horses and thundering arms of the strangers; but soon recovering from the effects of their first surprise, they intrepidly opposed their new enemies on the banks of the Rio-claro. Despising their force, and ignorant of their bravery, Almagro placed his Peruvian allies in the first line, now considerably increased by an additional number whom Paullu had drawn from the Peruvian garrisons in Chili. But these troops were soon defeated by the Promaucians, and fell back in confusion on the line of Spaniards in the rear. The Spaniards, instead of remaining spectators of the battle, were now compelled to sustain the vigorous attack of the enemy; and, advancing with their horse, a furious battle was fought with considerable loss on both sides, and continued till night separated the combatants without either party having gained the victory. [Footnote 63: Called _Puramaucans_ by Garcilasso and _Promocaes_ by Ovale, who names the _Cauquenes_ and _Peneos_ as their allies.--E.]