Spanish American wars of independence important change in strategy after three United Provinces campaigns had been defeated in Upper Peru. San Martín's army became the nucleus of the Army of the Andes, which received crucial political and material support in 1816 when Juan Martín de Pueyrredón became Supreme Director of the United Provinces. In January 1817, San Martín was finally ready to advance against the royalists in Chile. Ignoring an injunction from the congress of the Río de la Plata not to move against Chile, San Martín together with General Bernardo O'Higgins Riquelme, later Supreme Director of Chile, led the Army over the Andes in
Army of the North Goyeneche and Joaquín de la Pezuela, an able and experienced soldier, had the advantage, he negotiated with Goyeneche a 40-day armistice. The Assembly in Buenos Aires and the viceroy of Peru, José Fernando de Abascal, disapproved of this agreement. The royalists attacked by surprise, disregarding the agreement, before the arrival of reinforcements at the Battle of Vilcapugio on 1 October 1813. The royalist army, commanded by brigadier Joaquín de la Pezuela and with 4,000 men and 12 pieces of artillery confronted a patriot army with a high morale composed of 3,500 men, 14 pieces of artillery and cavalry mounted mostly