Battle of Maipú, 1818: the victory that secured Chile's independence

When San Martín heard that Maipú was won, he dictated a short report from the saddle: "We have just won the action completely. A small remnant is fleeing; our cavalry is pursuing it to the end. The homeland is free." The surgeon Diego Paroissien wrote it down with hands still bloody from the wounded. It was the battle on which the independence of Chile, and much of San Martín's plan for South America, depended.²

From Chacabuco to Cancha Rayada

In early 1817 San Martín had led the Army of the Andes across the mountains from Mendoza and beaten the royalists at Chacabuco on 12 February. The survivors held out in the fortress of Talcahuano and were then joined by a relief army sent by the viceroy of Peru, which landed near Concepción on 18 January 1818 under Brigadier Mariano Osorio. Among its units was the veteran Burgos regiment, which had fought against Napoleon's occupation of Spain. Bernardo O'Higgins proclaimed Chile's independence on 12 February 1818, the anniversary of Chacabuco.³

Osorio advanced north, took Talca and on the night of 19 March surprised the patriot army at Cancha Rayada and scattered it. Memoria Chilena calls the blow a surprise that caused heavy damage. O'Higgins was wounded in the elbow, and rumors spread that San Martín was dead.⁴

An army rebuilt in two weeks

San Martín rode to Santiago to show that he was alive and to restore public confidence. He had to find new munitions and guns, since his artillery had been lost at Cancha Rayada. By early April, according to the Argentine government's account, the United Army again had 5,400 men and 21 guns; the Instituto Nacional Sanmartiniano, synthesizing several sources, gives about 6,000 men and 21 guns against about 5,000 royalists with 12 guns.⁵

When Osorio learned that the patriots had regrouped he marched on Santiago from Talca. San Martín placed his army on the eastern part of Loma Blanca, south of the city, to bar the way, and the royalists camped near the Lo Espejo farm. He kept his infantry in the center with cavalry on both flanks: Colonel Juan Gregorio de Las Heras commanded the 1st Division on the north-west, Colonel Rudecindo Alvarado the 2nd on the south-east, and Colonel Hilarión de la Quintana the reserve behind them.⁶

The reserve decides the day

Around midday the patriot artillery under Manuel Blanco Encalada opened fire. The royalists answered and gave away their position, and San Martín sent both wings forward. Las Heras took a hill and threatened the royalist left, but Alvarado's division was thrown back by a royalist advance. San Martín then sent the reserve forward in an oblique movement to support Alvarado, which restored the line while Las Heras kept pressing the other flank.⁷

The royalist army began to break. Osorio, believing all was lost, left the field with his cavalry, and General José Ordóñez took over. Four royalist battalions, among them the Burgos, formed squares on the plain and refused to surrender or run. The Instituto Nacional Sanmartiniano recounts the cry from their ranks: "Here is the Burgos. Eighteen battles won, none lost." Their squares beat off cavalry and two infantry charges before they withdrew in order, under constant attack, to the buildings of Lo Espejo.⁸

The last stand at Lo Espejo

Some 2,000 royalists held the farm. A charge by the Coquimbo battalion was driven back, then San Martín massed 17 guns against the buildings and the patriots stormed them. Ordóñez and Primo de Rivera surrendered. Before the end, O'Higgins, still convalescent from his wound, arrived with about 1,000 more men. The two commanders embraced on horseback, the scene later known as the Embrace of Maipú, and San Martín told him that Chile would never forget "the illustrious invalid" who had come to the battlefield in that state.⁹

San Martín later wrote that he had rarely seen an attack braver, faster and more sustained, nor a resistance more vigorous and stubborn. The Instituto Nacional Sanmartiniano puts patriot losses at about 1,000 and royalist losses at about twice that, with some 3,000 prisoners and a large quantity of arms taken.¹⁰

What Maipú meant

Memoria Chilena calls the victory fundamental to consolidating independence: it broke the royalist army physically and morally, and it withdrew to the south. Only minor actions followed in Chile, and the country began to prepare the expedition that would carry the war to Peru. The Argentine government's account stresses the lesson of the day: the timely use of the reserve.¹¹