The raid involving Imperial Japanese Navy midget submarines was part of Japan's broader strategy to assert its dominance in the Pacific during World War II. Sydney Harbour was targeted due to its strategic importance as a major base for Allied operations in the region. On the night of the attack, three midget submarines entered the harbour, two of which would ultimately become involved in a series of confrontations with Australian forces. These submarines aimed to sink allied naval vessels, impacting the logistics and morale of the Australian forces.

The attacks began with a torpedo strike on the HMAS Kuttabul, a converted ferry used as a naval base, which resulted in the sinking of the vessel. The incident led to significant casualties and marked the first hostile action on Australian territory during the war. While the attack did not achieve major military success, the psychological impact on Australian society was considerable, as it highlighted the vulnerability of the home front. Local defenses were subsequently strengthened in response to the perceived threat from Japan.

Following the attack, authorities launched extensive searches for the remaining submarines and ordered heightened defenses across Sydney, including air raid precautions. The incident spurred public discourse on Australia’s national security, leading to increased military recruitment and a greater sense of urgency in the war effort against Japan.