Peru was, as we have seen, the single greatest bastion of Spanish rule in South America during the decade after 1810. Its viceroys had stifl ed rebellion within the viceroyalty and held back revolution in Upper Peru, Quito, and Chile. However, royalist Peru faced its greatest test after 1820, when political upheaval in Spain and armed incursions from neighboring territories generated fresh challenges. San Martín presented the fi rst, inconclusive, challenge when he landed his expeditionary army at Pisco in 1820; the second, much more effective challenge originated when Bolívar entered the Peruvian theater of war in 1823. Indeed, Bolívar went on to become the nemesis of the Spanish Viceroy of Peru and, by 1825, was acclaimed as both the Liberator of Peru and the founder in Upper Peru of Bolivia, the state that bore his name.