Coastal fortifications of colonial Chile

In Colonial times the Spanish Empire diverted significant resources to fortify the Chilean coast as a consequence of Dutch and English raids.

Responding to this threat the viceroy of Peru sent in 1579 an expedition commanded by Pedro Sarmiento de Gamboa to the Strait of Magellan in order to explore the feasibility of fortifying it and by virtue of that controlling the entrance to the Pacific Ocean from the Atlantic.

[3] Back in the Strait of Magellan Sarmiento founded the cities of Nombre de Jesús and Ciudad del Rey Don Felipe in 1584.

There, realizing there was not enough food for all, Andrés de Biedma ordered the people to scatter along the northern coast of the strait and wait for any vessel that could provide aid.

The attack to be commanded by George Anson proved a complete failure even before the expedition reached Spanish ports: the ships had dispersed and HMS Wager wrecked off the coast of Patagonia.

[11][12] The coastal city of La Serena in northern Chile was first fortified in the 1730s, about fifty years after it was sacked and torched by the pirate Bartholomew Sharp.

[13] In the 1740s the viceroy of Peru and the governor of Chile converged in a project to advance the frontiers of the Spanish Empire in the Southeast Pacific and prevent the establishment of a British base.

Other vulnerable localities of colonial Chile such as Chiloé Archipelago, Concepción, Juan Fernández Islands and Valparaíso were also made ready for an eventual English attack.

[14][15] Inspired in the recommendations of former governor Santa María the Spanish founded the "city-fort" of Ancud in 1768 and separated Chiloé from the Captaincy General of Chile into a direct dependency of the Viceroyalty of Peru.

[17][18][19] A notable dissident was the Governor of Osorno Juan Mackenna who argued in an 1810 report for diminishing the size of the garrison protecting Valdivia and distribute resources aimed at it elsewhere.

[20] Mackenna's thesis that controlling fortified positions was unnecessary to conquer a territory was contradicted both by the experiences of the Peninsular War and by Cochrane's decision to attack the Valdivia Fort System itself in 1820.