The first independence movements in South America came shortly after Spain was seized by Napoleon Bonaparte in 1808. Peruvian officials remained loyal to the Spanish throne, and the viceroy was quick to send troops to rebellious spots in neighboring regions as well as in his own.

The revolutionary forces gained strength, however, and in 1818 Chile, with the assistance of José de San Martín of Argentina, won independence. The revolutionists launched an invasion of Peru in 1820, and Lima fell without a struggle in 1821. San Martín assumed authority as “Protector of Peru," but in 1822 returned to Chile. In 1824 Spain sent forces to reconquer Peru, but aided by Simón Bolívar and Antonio José de Sucre the patriot army won a decisive victory at Ayacucho. The Spanish held Callao until 1826.