HMAS Adelaide was a Town-class light cruiser of the Royal Australian Navy (RAN), named after Adelaide, the capital city of South Australia. Laid down in 1915, wartime shortages and design modifications meant the ship was not completed until 1922, earning her the nickname "HMAS Longdelayed".

A blockade runner is a merchant vessel used for evading a naval blockade of a port or strait. It is usually light and fast, using stealth and speed rather than confronting the blockaders in order to break the blockade. Blockade runners usually transport cargo, for example bringing food or arms to a blockaded city. They have also carried mail in an attempt to communicate with the outside world.