Army of the Andes have it being as high as 6000 men. The army consisted of Argentines and Chileans, and included some 1200 auxiliaries to help in provisioning and supply, as well as a complement of artillery. The Congress of Tucumán endorsed San Martín's proposal to form an army to fight the royalists in Chile, and between August 1814 and February 1817, San Martín trained his troops to prepare them for their ordeal. While the army was made up of a less than experienced military force, San Martín intended to lead, with regular discipline and equipment, a proper army and not a "motley crew"
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".