Battle of Maipú Battle of Maipú 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. In 1817, the Argentine General José de San Martín led an army across the Andes and defeated the Spanish at the battles of Chacabuco and Chalchuapa and captured Santiago. The Spanish viceroyalty sent a
José de San Martín that it was not possible to defend Concepción, so he ordered O'Higgins to leave the city. 50,000 Chileans took cattle and grain and moved north, burning everything else, so that they did not leave supplies for the royalists. As he had done with the Tucumán Congress, San Martín urged a declaration of independence, to legitimize the government and the military actions. The Chilean Declaration of Independence was issued on 18 February 1818, one year after the battle of Chacabuco. San Martín, Las Heras and Balcarce met in Curicó, and the royalists in Talca, in a plain known as "Cancha rayada".