After failing to capture the Spanish fortress of Real Felipe in El Callao, Cochrane decided to assault the city of Valdivia, the most fortified place in South America at the time. Valdivia was considered a threat to Chilean independence as it was a stronghold and supply base for Spanish troops. Valdivia provided a safe landing site for sending reinforcements to the loyalist guerrilla fighting the Guerra a muerte in the area of La Frontera. Valdivia was isolated from the rest of Chile by native Mapuche territory, and the only entrance to Valdivia was Corral Bay, at the mouth of Valdivia River. The bay was protected by several forts built to prevent pirate raids or any attack from a foreign nation.
Fortifications
The defenses at Valdivia consisted of a number of forts and defensive positions. On the South side of the harbour were four forts - Fort Inglés, Fort San Carlos, Fort Amargos and Fort Chorocomayo. Further inland was Corral Castle to defend against a landward assault. On the Northern side was the stone walled Fort Niebla. Mancera Island in the centre of the harbour was also heavily garrisoned.
Battle
Facing these powerful fortifications, Lord Cochrane decided to attack the forts from the land in an amphibious nighttime operation. The troops landed south of the bay on the Aguada del Inglés. Taken by surprise, the Fort Inglés was captured quickly, with the fugitives running towards the next fort, Fort San Carlos. The attackers got in among the fleeing Spanish troops and in the confusion were able to capture San Carlos and subsequently the other two forts on the south side of the harbour, with only Fort Chorocomayo showing brief resistance before capitulating. After the success of the attack on the forts of the southern shore, Cochrane called a halt for the night. He anticipated an altogether grimmer fight in the morning to capture the remaining fortifications, as he had lost the element of surprise. However, in the morning the commanders of the other forts unexpectedly decided to surrender without a fight, with the garrisons of Fort Niebla and Mancera Island retreating upstream. The town of Valdivia surrendered soon after.
Aftermath
The Spanish troops inside Valdivia itself sacked the city and then went to Osorno. These troops later moved to reinforce Chiloé Island which was the last Spanish possession in Chile. Lord Cochrane tried to conquer the island without success. The capture of Valdivia effectively ended the last vestiges of Spanish power in mainland Chile and opened up the way for Chilean and Peruvian independence.
