The campaign was developed from September 12, 1819 with the departure of the Chilean squadron from Valparaíso to Callao to begin the so-called first blockade of Callao and ended in 1822, coinciding with the surrender of the Spanish frigates "Prueba" and "Venganza", and the corvette "Emperador Alejandro" to the government of the Free Province of Guayaquil, in February 1822, due to the absence of ports and supplies, a product of the territorial conquests of the independent states.

The campaign had the added difficulty that the Spanish squadron could take refuge in Callao, which had around 350 siege cannons and a real floating trench, the product of the ingenuity of Brigadier Antonio Vacaro, made up of logs joined by chains that barely left a narrow entrance and prevented an effective attack to finish off the Spanish.

Cochrane had used various methods to capture or destroy the Spanish squadron stationed in the port, of which we can highlight the use of Congreve rockets, which had a disappointing result.

After two expeditions to Peru, where Cochrane had twice blockaded the port of Callao and attacked its surroundings, he headed towards the southern coast of Chile with the aim of capturing the second most important royalist enclave, which was in Valdivia.

After convincing himself that the San Telmo ship , the flagship of the South Sea Division, with 74 cannons and 650 crew members, was not waiting for him, he ordered an invasion, managing to capture the town of Valdivia after a daring attack on 3 and 4 February 1820.