General San Martín was one of the most important liberators (someone who releases people from oppression or captivity) fighting against the Spanish.
During the 19th century (the 1800s), the Spanish-American wars of independence were happening. Spain had control of Argentina during this time due to colonization (establishing control over the indigenous people of an area). The people of Argentina did not agree with this ruling. Argentina wanted independence from Spain because Spanish people held all the government positions and therefore were in control of the Argentinian people.
San Martín was actually in the Spanish army for 20 years before joining the revolution in Argentina. General San Martín's genius-level tactic was to cross the Andes mountains by horse to attack which no one was expecting. This action was a huge factor in Argentina's winning the war.
After he helped Argentina, Peru and Chile defeat the Spanish army, he went into exile but remained a national hero for Argentina, Chile and Peru. His tomb currently rests inside the Catedral Metropolitana in Plaza de Mayo in Buenos Aires, Argentina.
