San Martín’s Victory at Maipú Secures Chile’s Independence

On April 5, 1818, the royalist army of the Spanish Empire and the combined patriot forces clashed on the plains of Maipú, just south of Santiago. Less than three weeks earlier, the royalist general Mariano Osorio had dealt the patriots a punishing surprise blow at the Second Battle of Cancha Rayada. That setback threatened to undo the territorial gains achieved after the crossing of the Andes in 1817, but the patriot leadership managed to salvage their core formations and reorganize near the capital within days.

The patriot army reorganized quickly near Santiago in the days after the defeat. By early April, Argentine general José de San Martín commanded roughly 5,000 to 6,000 soldiers supported by 21 artillery pieces, against roughly 4,000 to 5,000 royalist troops and 12 guns under Osorio's command, depending on the source.