Sydney Harbour defences

Fort Phillip was also built to protect from a potential French invasion in 1804, as well as following the Castle Hill convict rebellion the same year.

More permanent fortifications were built during the first half of the 19th century in response to feared foreign attacks[3] with new threats to the British Empire, including Napoleon's French troops in 1810, and the Russian Pacific Fleet in the 1850s (during the Crimean War).

[4] Although only a courtesy visit, the event demonstrated the settlement's vulnerability to attack and highlighted awareness of its isolation and wealth.

Minefields were laid across the main shipping channels of Port Jackson from 1876 to 1922 and a base was built at Chowder Bay for the submarine miners (Clifton Gardens).

Sydney's defences were expanded over the last decades of the 19th century and eventually incorporated a fort on Bare Island to defend the approaches to Botany Bay.

During the 2000 Sydney Olympics security for the Harbour was provided by Special Forces, Navy Clearance Divers and warships.