HMAS Sydney was a Chatham-class light cruiser of the Royal Australian Navy (RAN). Laid down in 1911 and launched in 1912, the cruiser was commissioned into the RAN in 1913.

The Town class was a group of twenty-one light cruisers built for the Royal Navy (RN) and Royal Australian Navy (RAN) of the first half of the 20th Century. These vessels were long-range cruisers, suitable for patrolling the vast expanse covered by the British Empire. These ships, initially rated as second class cruisers, were built to a series of designs, known as the Bristol, Weymouth, Chatham, Birmingham and Birkenhead classes – all having the names of British towns except for the RAN ships, which were named after Australian cities.