The combat began at dawn, with intense cannon fire and rocket discharges over the Argentine batteries, which had less accurate and slower loading cannons. From the beginning the Argentines suffered many casualties — 150 dead, 90 wounded. Furthermore, the barges that held the chains were burnt down, and the "Republicano" was lost, blown up by its own commander when he was unable to defend it any longer. A number of armed launches were also sunk in battle. The gunboats "Restaurador" and "Lagos" disengaged successfully and withdrew up river, towards Tonelero pass. The third gunboat and the armed barges also survived the action, but the dismantled brigantine "Vigilante" was scuttled by her crew and the remaining launches were destroyed by the combined fleet on 28 November.