On 4th September 1944, convoy HI-72 sailed from Singapore. Two of these ships, Rakuyo Maru and the Kachidoki Maru carried PoWs. The Rakuyo Maru carried 1317 Pows and the Kachidoki Maru a further 900.
On the 12th of September the convoy was attacked by US submarines and both these ships were hit. The Rakuyo Maru was torpedoed by the US submarine Sealion at around 5:00am.
The Japanese rescued some of the POWs from these two ships and they continued their journey to Japan on the Kibitsu Maru.
When the US Submarines realised that they had sunk ships containing PoWs, they searched for survivors, picking up 63 PoWs from the Rakuyo Maru. Of these 4 died soon after being rescued.
The Rakuyo Maru lost 1159 prisoners to the sea and the after effects of being in the water for up to 4 days.