The Battle of Maipú was a battle fought near Santiago, Chile on April 5, 1818, between South American rebels and Spanish royalists, during the Chilean War of Independence.
The Patriot rebels led by Argentine general José de San Martín effectively destroyed the Spanish forces commanded by General Mariano Osorio, and completed the independence of the core area of Chile from Spanish domination.
The battle began when the Patriot artillery opened fire about 11:30 AM, being immediately contested by its Royalist counterpart, although inflicting no casualties upon each other. After a half-hour of useless shelling, San Martín ordered Las Heras and Alvarado to move forward. The infantry advanced in columns without retaliating fire, until Las Heras threw his troops against Primo de Rivera with the support of Blanco Encalada’s artillery, while Alvarado did the same against Ordoñez being covered by Borgoño’s batteries. The grenadiers under Zapiola were assailed by part of the Royalist cavalry, but managed to counterattack and chase the attackers to a little slope where they were decimated by a dense infantry and artillery fire.
Obliged to retreat, Zapiola was reinforced and attacked again, successfully dispersing the enemy’s cavalry and securing the Patriot right flank. During the fray, suddenly the Patriot reserve emerged from behind Las Heras and Alvarado’s lines and engaged Morla and Ordoñez divisions. Right after, the Cazadores squadrons led by Col. Ramón Freire dispersed the Spanish cavalry on the eastern flank. On this charge died Chilean Colonel Santiago Bueras.
On the centre, both infantries attacked each other with intensity. Ordoñez division, reinforced with another two units – the Burgos and Arequipa battalions – charged the Patriot line, forcing it to cede a little. However, San Martín sent three battalions to the sector – The 1st and 3rd infantry battalions plus the 7th Battalion of Los Andes -, and these assaulted and split the Burgos Battalion, while the Arequipa Battalion was completely disbanded.
The rest of the Royalist units formed in squares endured up to ten cavalry melees, but retreated after the centre and right wing withdrew to Lo Espejo. At this point Osorio deserted the field, leaving the Royalists under the command of Ordoñez.