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 (British and Australian) and the Kachidoki Maru a further 900 (all British).
On the 12th of September the convoy was attacked by US submarines and both these ships were hit. The Kachidoki Maru was torpedoed by the US submarine Pampanito at 22:40 hours.
The Japanese rescued some of the POWs from these two ships and they continued their journey to Japan on the Kibitsu Maru.
All of those who survived the sinking of the Kachidoki Maru jumped within the first ten minutes of the ship being hit.