In late May and early June 1942, during World War II, Imperial Japanese Navy submarines made a series of attacks on the Australian cities of Sydney and Newcastle.

Visit Australian War Memorial - https://www.awm.gov.au/visit

Royal Australian Navy Naval Heritage Centre - https://www.navy.gov.au/ran-heritage-centre

Fort Scratchley - https://www.newcastle.nsw.gov.au/fort-scratchley/fort-scratchley-home

More information

Navy - https://www.navy.gov.au/history/feature-histories/japanese-midget-submarine-attack-sydney-harbour

Sea Museum - https://www.sea.museum/2017/06/14/midget-submarine-attack-on-sydney-31-may-1-june-1942

ANZAC Memorial - https://www.anzacmemorial.nsw.gov.au/our-stories/our-stories/japanese-submarines-sydney-harbour

Woolahra council - https://www.woollahra.nsw.gov.au/library/local_history/world_war_2/stories_from_woollahra/shelling_of_the_eastern_suburbs

A brilliant book on the subject is 'A Very Rude Awakening - The Night The Japanese Midget Subs Came To Sydney Harbour' by: Peter Grose - https://amzn.to/3HrFJy0