Queensland State Archives posted a photo:
The Australian colonies were part of the British Empire, which had made many enemies by the nineteenth century when other colonial powers were rapidly expanding their empires. At the time the fort was built, Brisbane had fewer than 100,000 people, with an annual trade worth more than four million pounds.
Brisbane was more vulnerable to naval attack than Sydney or Melbourne as it was just three days’ sail from the French naval garrison at Noumea. Local defences were essential as Moreton Bay had numerous islands on which the enemy could establish a base.
Based on the recommendations of the illustrious British soldiers and military tacticians Colonel Sir William Jervois and Scratchely, Queensland opted to rely heavily on Fort Lytton as a fixed defence position for its capital and wealthiest port, Brisbane.
Description source:
Wikipedia
View the original record at the Queensland State Archives:
Item ID 2692229