In the latter part of May and the early weeks of June 1942, Japanese midget submarines attacked shipping in Sydney harbour. Although originally designed for harassing enemy surface vessels during large-scale fleet actions, the Japanese mini-subs were used almost exclusively in WWII for attacking shipping in Allied harbours. (The Italians had used ‘ manned torpedoes ‘ for attacking British battleships in Alexandria harbour in December 1941.)

All three midget submarines involved in the attack were eventually lost, but not before one of them had shelled Sydney Harbour bridge, this week in the war, on the morning of 8 June 1942. Another shelled the coastal town of Newcastle on that same morning.

Damage inflicted by the shelling was minimal but the presence in Australian waters of the parent submarines (that had transported the midget submarines) prompted the Australian Navy to introduce a convoy system to protect Allied merchant vessels.