The sinking of the Junyo Maru in September 1944, one of the deadliest maritime disasters in history. It occurred when the unmarked Japanese ship carrying around 5,750 POWs and forced laborers, was torpedoed by the British submarine HMS Tradewind.

Over 5,000 passengers perished as the ship rapidly sank.



The Junyo Maru, originally a cargo vessel, was built in 1913. Prior to its requisition by the Japanese military, it served as a commercial ship primarily operating in East Asian waters. This vessel, like many others during the peaceful years, was involved in the transport of goods and passengers, contributing to the economic connectivity in the region. Its transition from a civilian to a military role was a direct consequence of the changing geopolitical landscape with the onset of World War II.

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With the outbreak of World War II and the expansion of Japanese territorial ambitions, there was a significant shift in the usage of maritime resources. The Japanese military began requisitioning civilian ships for military purposes, a common practice among nations during the war. The Junyo Maru was one such vessel that was commandeered to aid in Japan’s war efforts. Its size and capacity made it suitable for transporting large numbers of troops, supplies, and later, prisoners of war and forced laborers.

The Junyo Maru pictured in 1933.

As part of the Japanese war machine, the Junyo Maru played a critical role in supporting the vast network of labor camps spread across the Japanese-occupied territories. These camps were integral to Japan’s strategy of utilizing forced labor for military and infrastructure projects. The ship was used to transport POWs and romusha, who were often subjected to inhumane conditions. The romusha were mostly local inhabitants from occupied territories, coerced into labor.

The treatment of POWs and romusha during their transport on ships like the Junyo Maru was notoriously brutal. Overcrowding, insufficient food and water, poor sanitation, and lack of medical care were common. These conditions were reflective of the Japanese military’s disregard for the Geneva Conventions, which set the standards for the humane treatment of prisoners of war.

The Hell Ship

As World War II progressed, the Japanese military’s demand for labor in their occupied territories intensified. The Junyo Maru was assigned to transport a large number of prisoners of war (POWs) and romusha (forced laborers) to support this effort. Prior to departure, these individuals were gathered under dire conditions, often with minimal regard for their health or well-being. The POWs, including Dutch, British, Australian, and American nationals, were typically captured soldiers, while the romusha were civilians from occupied regions, coerced into labor.

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On September 18, 1944, the Junyo Maru set sail from Batavia (now Jakarta, Indonesia) to Padang. The ship was severely overcrowded, carrying approximately 4,300 forced laborers and around 1,450 Allied POWs.

This overcrowding was a common issue with hell ships, the term used for Japanese ships transporting POWs and laborers under inhumane conditions. The cramped and unsanitary conditions on board posed serious health risks, exacerbating the suffering of the passengers.

The ship was ill-equipped to handle such a large number of people, lacking adequate food, water, and medical supplies. Sanitation facilities were woefully insufficient for the needs of the passengers, leading to unhygienic conditions. Furthermore, the Junyo Maru was not marked according to the Geneva Convention to indicate it was carrying POWs. This lack of identification as a POW transport ship was a grave violation of international law and would have severe consequences during the voyage.

The journey was fraught with danger, as Allied forces were actively targeting Japanese shipping routes to disrupt supply lines. The waters around the Indonesian archipelago were particularly hazardous due to the presence of Allied submarines. The Japanese, aware of these risks, often chose not to mark their ships to avoid detection, thereby putting the lives of POWs and civilians at greater risk.

The Sinking Of The Junyo Maru

The Junyo Maru was sailing through the Indian Ocean off the west coast of Sumatra when it was targeted by the British submarine HMS Tradewind on September 18, 1944. The Tradewind, under the command of Lieutenant Commander S.L.C. Maydon, was patrolling the area as part of Allied efforts to disrupt Japanese supply lines. Unbeknownst to the crew of the Tradewind, the Junyo Maru was carrying thousands of POWs and romusha, as the ship was not marked in accordance with international conventions to indicate it carried non-combatants.

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The HMS Tradewind fired four torpedoes at the Junyo Maru, which struck the ship, causing catastrophic damage. The impact was devastating, and the ship began to sink rapidly. The overcrowded conditions and lack of preparation for such an emergency compounded the chaos and panic among the passengers.

The British submarine HMS Tradewind.

In the aftermath of the torpedo strike, the situation aboard the Junyo Maru quickly turned disastrous. The ship lacked sufficient lifeboats and life-saving equipment, and many of the passengers could not swim. This, combined with the overcrowded conditions, made it extremely difficult for individuals to escape the sinking vessel. Moreover, the shock and suddenness of the attack left little time for an orderly evacuation.

The casualty rate was alarmingly high. It’s estimated that around only 680 of the approximately 5,750 individuals aboard survived. They were picked up the next morning by a Japanese vessel.

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The sinking raised questions about the tactics used by the Allies in targeting enemy ships. The crew of HMS Tradewind was unaware that the Junyo Maru carried POWs and civilian laborers, highlighting the complexities and moral dilemmas faced in wartime decisions. This incident underscored the tragic consequences of warfare, where the lines between military and civilian targets were often blurred, leading to significant loss of innocent lives.

The Aftermath

The immediate aftermath of the sinking was marked by immense loss of life. Over 5,000 individuals, comprising POWs and romusha, perished. The enormity of this loss ranks the sinking of the Junyo Maru among the deadliest maritime disasters in history. The tragedy was compounded by the fact that many of the victims were non-combatants, who were already enduring the hardships of forced labor and imprisonment.

The survivors faced harrowing conditions. Those who managed to escape the sinking ship had to endure open ocean, with many succumbing to exhaustion, dehydration, or shark attacks. Approximately 680 individuals survived the initial sinking, but their ordeal was far from over. Once rescued, they were often met with continued hardship. The POWs were typically relocated to other camps, where they faced further brutality and forced labor under harsh conditions.