On the 20th of August the fleet of seventeen vessels carrying the whole revolutionary army suddenly appeared a few miles north of Valparaiso. Balmaceda had short warning and was not able to oppose the landing, which was skilfully conducted by Colonel Canto, the able strategist who commanded the congressionalist forces, with the valuable assistance of Colonel Koerner, a Prussion tactician of the first rank whose services had been hired. There was no time to get troops from Coquimbo and Concepcion. The congressionalist generals moved so rapidly that the best the president could do was to send the Santiago division, which, united with that at Valparaiso, made a force nearly equal in numbers to the enemy. The revolutionists landed with their rations in their haversacks and within a few hours were marching straight south along the seashore on Valparaiso. The Balmacedists tried to defend the passage of the Aconcagua River, which enters the ocean twenty miles north of the city, but they had hardly got into position on the heights which overlook its southern bank when the enemy was upon them. The latter's artillery was twice as strong and his infantry more numerous besides being armed with longer range rifles. In spite of the advantage of position and the fatigue of their opponents the Balmacedists were flung back in complete defeat by the volleys of the Mannlichers and the furious cannonading from both batteries and ships. The battle lasted the whole day and at its close two thousand of the government troops lay on the field, three thousand had been dispersed or deserted to the enemy, and scarcely three thousand held together for the retreat to the neighbourhood of Valparaiso, where three regiments of the Santiago division who had taken no part in the fight were waiting. Canto followed, but failing in a tentative attack on the strong northern defences of Valparaiso, he determined to make a circuit to the east, cut the railroad between Santiago and Valparaiso, and either take the latter place in the rear or march on the capital as seemed best. The movement, so masterfully conceived, was skilfully carried out without a moment's loss of time. The essential thing was to act so promptly that Balmaceda could not concentrate his forces. On the 25th the whole congressionalist army had reached Quillota, on the railroad twenty-five miles back of Valparaiso. But Balmaceda had also been active, and during those three days the Concepcion division had arrived at Santiago, and reinforcements had been got through to Valparaiso which raised the army to nearly ten thousand men. Four thousand troops defended Santiago and more were momentarily expected from Coquimbo.