In Los Infantes captain Lorenzo Bernal del Mercado had discovered that the rebels had constructed a pucará close by, establishing a blockade of the city. Lorenzo Bernal ordered a reconnaissance patrol and he observed that the natives under the toquiIllangulién had chosen an impregnable position in a marsh and chose to retire. Illangulién's troops then moved to a second position, nearer to Angol, to which captain Lorenzo Bernal responded with a new reconnaissance.
Finding that this new position also was impregnable he again retired. Feeling victorious and believing the destruction of Angol was imminent, a Mapuche detachment located themselves in a third position awaiting reinforcements from their main body at the old position. This time, seeing their dangerous proximity to Los Infantes, captain Bernal chose to attack the position before more Mapuches arrived. In the battle the Spanish drove the Mapuche out of their pucara and pursued them down to the river bank and drove them into the river, where they were trapped and 1,000 Mapuches were killed including the toqui Illanguelén and many more were wounded or captured. Bernal ordered some of the captives killed and others lost hands or feet. When the news reached the rest of the Mapuche army coming to attack Angol they dispersed.