Tilbury Fort is one of the finest surviving examples of 17th-century military engineering in England. Built on the site of a smaller Tudor fort, it was designed to defend the river Thames passage to London against enemy ships. It was in nearby West Tilbury that Elizabeth I famously rallied her makeshift army awaiting the Armada in 1588.
Tilbury’s precise geometric design provided multiple lines of fire across the river and twin moats. However, its defences were never tested by any enemy. Though it became obsolete at the dawn of the 20th century, it remained garrisoned until the end of the First World War.