Battle of Maipú

The Battle of Maipú, fought on the plains just south of Santiago on 5 April 1818, was the decisive clash of the Chilean War of Independence. A combined Chilean and Argentine army under José de San Martín shattered the royalist army of General Mariano Osorio, securing the independence of central Chile from Spain and opening the way for patriot campaigns further north along the Pacific coast.

In 1817 San Martín took an army over the Andes from Argentina, defeated the Spanish at Chacabuco and took Santiago. The Spanish authorities sent a new army under Osorio, which defeated the patriots at the Second Battle of Cancha Rayada. The setback was serious but not fatal. Within two days the patriot army had regrouped around a core of about 4,000 men, and Bernardo O'Higgins, the Chilean leader, worked to rebuild it: he recovered weapons that had been handed out to civilians, requisitioned arms from Santiago's merchants and residents, hurried supplies from Los Andes and set up a training camp at Ochagavía. Osorio, meanwhile, advanced slowly northwards against local resistance. By 2 April the patriots fielded three infantry divisions with roughly 5,000 officers and men.

On the night of 4 April the royalists camped at Lo Espejo, about seven kilometres from the patriot lines. San Martín drew up his army on low hills the next morning, with Las Heras' division on the right, Alvarado's on the left and Quintana's in reserve behind them, mounted grenadiers on the far right and artillery under Blanco Encalada and Borgoño. Osorio formed his men on a triangular ridge north of Lo Espejo, with divisions under Primo de Rivera, Morla and Ordóñez. Each side numbered about 5,000, but the patriots had 21 guns against 12.

The patriot artillery opened fire at about half past eleven, with little effect on either side. San Martín then sent his infantry forward in columns. On the right, royalist cavalry attacked the grenadiers under Zapiola, who drove them back and secured that flank, while on the eastern flank Colonel Ramón Freire's cavalry scattered the Spanish horse; the Chilean colonel Santiago Bueras was killed in the charge. In the centre the fighting was fierce. Ordóñez's division, reinforced by the Burgos and Arequipa battalions, pushed the patriot line back until San Martín committed three more battalions, which broke the Burgos battalion and routed the Arequipa battalion.

As the royalist centre and right fell back to Lo Espejo, Osorio left the field, leaving Ordóñez in command. Ordóñez made a last stand at the farm buildings there, inflicting heavy losses on a rash frontal charge, until patriot artillery pounded the position and his men were forced to surrender. Militia brought up by O'Higgins rounded up the scattered fugitives.

Figures vary between accounts. One gives about 1,500 royalist dead and 2,289 prisoners, against 800 patriots killed and 1,000 wounded; others give higher royalist losses. The victory ended major Spanish operations in Chile and allowed the Chilean and Argentine forces to carry the war to Spanish positions on the Pacific coast, culminating in the liberation of much of Peru from Spanish rule.

After the battle San Martín and O'Higgins embraced, a moment remembered in Chile and Argentina as the "Abrazo de Maipú". Every 5 April a civil and military parade is held at Maipú, and the day is also Armour Day for the Chilean Army.

Our 1815 map shows central Chile still within the Spanish Viceroyalty of Peru, and the 1880 map shows the independent Chilean state.