Viceroyalty of Peru arrived in Lima with Antonio José de Sucre to plan the offensive. In February 1824 the royalists briefly regained control of Lima. Olañeta's Rebellion started by surprise and the entire royalist army of Upper Peru (today's Bolivia) revolted, led by Pedro Antonio Olañeta (royalist) against La Serna, the viceroy of Peru (a liberal). This broke the royal army and started a civil war in Upper Peru. Having regrouped in Trujillo, Bolívar in June led his rebel forces south to confront the Spanish under Field Marshal José de Canterac. The two armies met on the plains of Junín on August 6,
Protectorate of Peru independence of Peru by José de San Martín on July 28, 1821. During the Peninsular War (1807–1814) central authority in the Spanish Empire was lost and many regions established autonomous juntas. The viceroy of Peru, José Fernando de Abascal y Sousa was instrumental in organizing armies to suppress uprisings in Upper Peru and defending the region from armies sent by the juntas of the Río de la Plata. After success of the royalist armies, Abascal annexed Upper Peru to the viceroyalty, which benefited the Lima merchants as trade from the silver-rich region was now directed to the Pacific. Because of