During World War II, Allied prisoners of war (POWs) and forced labourers coined the term "hell ships" for the Japanese merchant vessels used to transport them to labour camps. Approximately 126,000 Allied POWs endured these floating dungeons, which were infamous for extreme overcrowding, rampant disease, deliberate starvation, and brutal violence.

Freighters designed for 100 to 150 passengers were packed with thousands of men. POWs were jammed into stifling, unventilated holds with no room to sit or lie down. Captives were routinely denied adequate water, sanitation, and fresh air. Many men died of dehydration, heat exhaustion, and rampant dysentery.

Because the Japanese military refused to mark these vessels as POW carriers, Allied submarines and aircraft frequently attacked them. An estimated 21,000 Allied prisoners died, with the majority perishing from these "friendly fire" sinkings or being abandoned or executed in the water by Japanese forces afterward.

Eight Japanese ‘Hell Ships’ were attacked by allied forces during September 1944. So far it has been possible to identify 32 men from Nottinghamshire who perished on three of these vessels – the Kachidoki Maru and Rakuyo Maru, the Hofuko (Toyofuko) Maru.

On September 4th 1944, the Rakuyo Maru carrying 1,317 POWs and the Kachidoki Maru with 900 prisoners on board sailed from Singapore. Unaware these vessels carried POWs, American submarines attacked the convoy.

Two ships transporting pows were lost on 12th September. Rakuyo Maru was torpedoed by the USS Sealion. 1,005 prisoners were lost and only 259 survived. Kachidoki Maur was sunk by the USS Sealion. 244 POWs died, whilst 656 survived.

Hofuko Maru was sunk by allied bombers off Luzon. Putting to sea again having unloaded sick and dying prisoners, she resumed her voyage and was hit again. 1,000 prisoners died and 200 survived.