When WWII struck the heart of Australia: Japan's midget submarine attack on Sydney Harbour

By 1942, World War II had been raging for nearly three years. In the Pacific, the Empire of Japan had embarked on a campaign of rapid expansion, seizing territories across Southeast Asia and the Pacific Islands.

Their successes had brought them alarmingly close to Australia, a key member of the Allied forces and a crucial base for operations in the Pacific.

Japan's strategic objectives in the Pacific were twofold. Firstly, they aimed to secure the resources needed to sustain their war effort, particularly oil, rubber, and iron ore, which were abundant in the Southeast Asian territories they sought to control.

Secondly, they intended to establish a defensive perimeter of fortified islands and territories, which they believed would deter the Allies and buy them time to consolidate their gains.

Australia, with its strategic location, significant resources, and status as a member of the Allies, was a natural target for Japanese aggression.

However, a full-scale invasion was deemed too risky and resource-intensive by the Japanese high command.

Instead, they opted for a strategy of isolation, intending to cut off Australia from American support by capturing key locations such as New Guinea and the Solomon Islands.

The Japanese midget submarine program was a unique and innovative aspect of the Imperial Japanese Navy's warfare strategy during World War II.

The program revolved around the development and deployment of small, two-man submarines known as Ko-hyoteki-class submarines.

These vessels were designed for stealth and surprise attacks, capable of infiltrating enemy harbors and launching torpedoes against unsuspecting warships.

The midget submarines were approximately 78 feet long and 6 feet wide, powered by a battery-operated electric motor.

They were armed with two torpedoes and were designed to be launched from larger "mother" submarines.

The midget submarines were capable of reaching speeds of up to 23 knots and had a maximum operational range of about 100 nautical miles.

Despite their small size, these submarines were technologically advanced for their time, featuring a complex system of ballast tanks that allowed them to dive and surface rapidly.

The crews for these submarines were selected from the best and brightest within the Imperial Japanese Navy.

These men underwent rigorous training, both in handling the submarines and in the tactics of stealth and surprise.

They were expected to navigate challenging coastal waters, avoid detection, and launch their attacks with precision.

The missions were considered highly dangerous, and the submariners were often regarded as expendable - a testament to the extreme dedication and sacrifice expected of them.

The midget submarine program was a high-risk, high-reward strategy for the Japanese.

While the submarines had the potential to inflict significant damage, they also faced numerous challenges.

These included mechanical failures, navigational errors, and the difficulty of penetrating enemy defenses.

The idea for the attack was conceived following the successful midget submarine attack on Pearl Harbor in December 1941, which demonstrated the potential of these vessels for surprise assaults on enemy harbors.

In the months leading up to the attack, Japanese reconnaissance aircraft conducted several flights over Sydney, gathering crucial information about the harbor's defenses, shipping traffic, and potential targets.

These flights were often disguised as civilian aircraft, allowing them to operate undetected.

The intelligence gathered from these flights was used to create detailed maps and models of the harbor, which were then used to plan the submarine's routes and attack strategies.

The decision to launch the attack was made by Admiral Isoroku Yamamoto, the commander-in-chief of the Japanese Combined Fleet.

Yamamoto was a proponent of aggressive, unconventional tactics, and he saw the midget submarine attack as a way to disrupt the Allies' operations in the Pacific and demoralize the Australian public.

The attack was planned for the night of May 31, 1942. Three midget submarines, each manned by a two-member crew, were to be launched from larger "mother" submarines off the coast of Sydney.

The midget submarines were to infiltrate the harbor, launch their torpedoes against Allied warships, and then scuttle themselves to avoid capture.

The planning for the attack was carried out in utmost secrecy, with only a select few within the Japanese high command aware of the operation.

This secrecy was maintained even among the crews of the midget submarines, who were only informed of their mission shortly before their departure. 

The night of May 31, 1942, marked a dramatic and tense episode in the annals of World War II.

As darkness fell over Sydney Harbour, three Japanese midget submarines, each manned by a two-member crew, prepared to launch their audacious assault.

Their target: the Allied warships anchored unsuspectingly in the harbour.

The midget submarines were launched from larger "mother" submarines stationed off the coast of Sydney.

Navigating through the darkness and the harbour's natural and man-made obstacles, the submarines attempted to infiltrate the harbour's defenses.

Their primary targets were the heavy cruiser USS Chicago, the seaplane tender HMAS Albatross, and the depot ship HMAS Kuttabul.

The first midget submarine, M-14, was detected by the harbour's defenses at around 8 pm, caught in the anti-submarine net that protected the harbour.

Under attack from the Australian naval vessels, the crew chose to scuttle their submarine, ending their mission prematurely.

The second midget submarine, M-21, managed to penetrate the harbour's defenses and entered the harbour around 10 pm.

It fired two torpedoes at the USS Chicago, but both missed their target. One of the torpedoes hit the breakwater near the Kuttabul, causing an explosion that sank the converted ferry and resulted in the death of 21 sailors.

The third midget submarine, M-24, entered the harbour undetected and disappeared.

Its fate remained a mystery until its wreck was discovered in 2006, lying on the ocean floor off Sydney's northern beaches.

It is believed that this submarine also fired at the USS Chicago but missed.

The immediate aftermath of the midget submarine attack on Sydney Harbour was marked by shock, confusion, and a rapid response from the Australian military and government.

The attack had resulted in the death of 21 sailors aboard the HMAS Kuttabul, the only direct casualties of the assault.

The converted ferry was the unintended victim of a torpedo intended for the USS Chicago, and its sinking marked the most significant loss of the attack.

In the hours following the attack, the harbour was in a state of high alert. Naval vessels and aircraft scoured the waters for signs of the enemy submarines, while anti-aircraft batteries were prepared for a potential follow-up air attack.

The damaged and sunken submarines were recovered, and the bodies of two Japanese submariners were found, providing the first solid evidence of the attackers' identity.

The Australian government responded swiftly to the attack. Prime Minister John Curtin issued a statement acknowledging the attack and assuring the public that the situation was under control.

He emphasized the bravery and efficiency of the Australian defence forces in responding to the attack and urged the public to remain vigilant and prepared for further potential attacks.

Meanwhile, the military initiated a thorough investigation into the attack, aiming to understand how the enemy submarines had managed to penetrate the harbour's defenses and how similar attacks could be prevented in the future.

The attack had revealed vulnerabilities in Sydney's defenses, and the military was determined to address these shortcomings to ensure the city's future safety.

The public reaction to the midget submarine attack on Sydney Harbour was one of shock and fear, but also resilience.

For many Australians, the attack shattered any lingering illusions of their nation's invulnerability to the global conflict.

The war had arrived on their doorstep, in the heart of one of their most populous cities.

The news of the attack spread rapidly, leading to widespread anxiety about the possibility of further attacks.

However, alongside this fear, there was also a surge of national unity and determination.

Australians rallied around their government and military, demonstrating a collective resolve to face the challenges of the war.

The attack served to galvanize the public, reinforcing the importance of the war effort and the need for vigilance and preparedness.