Apart from the prisoners, 778 Japanese troops and 25 Japanese guards were also onboard.

There were only four lifeboats that were reserved for the Japanese troops. Four of the six life rafts were for them, too, so the remaining two were left for the more than a thousand prisoners in case something came up.

They sailed in good weather. The prisoners were sometimes allowed on deck so they could breathe some fresh air or stretch a bit.

Hit by USS Grouper

On the night of September 30, the USS Grouper sighted a group of nine sampans and a large freighter in the East China Sea, but they were not able to launch an attack immediately because of the moonlight. The next morning, as the prisoners were getting ready for the roll call, the Americans only saw the Japanese troops on board, unaware that they were, in fact, carrying prisoners. Grouper fired four torpedoes, one of which scored a hit. The freighter changed course and was left lying dead in the water, but it started firing at the submarine with a small-caliber weapon.

Inside, the prisoners were shaken by the explosion, the lights went out, and they were left completely in the dark. They also knew that the Japanese troops were hustling down, although no one was telling them what was happening. Before 9 am, USS Grouper fired another torpedo and missed.

The Americans spotted a bomber in the air around the Lisbon Maru before they fired the last torpedo. After they fired, three charges went off. After seeing the bomber and not the freighter, they incorrectly assumed that the ship had sunk.

As for the Japanese on the freighter, they suddenly became unresponsive to the prisoners’ requests— food, eater, latrine breaks. The POWs knew that the Lisbon Maru was just floating dead in the sea and that it had titled to one side. However, they were unaware that the 778 Japanese troops were already being transferred to the destroyer “Kure” that arrived late afternoon. Toyokuni Maru also arrived, and they had a discussion on what they would do with the Lisbon Maru. It was decided that the remaining troops would be transferred to the Toyokuni Maru while the crew and the prison guards would stay on board while Lisbon Maru was towed.

Lieutenant Wada, leader of the Japanese guards, ordered for the hatches to be closed as he was worried that the prisoners would escape and there was not enough manpower to handle them. The captain of the ship disagreed, knowing the risk that the prisoners might drown with no chance of survival in case Lisbon Maru sank, but the hatches were closed in the end.

Inside, the prisoners were literally in the dark with no airflow, food, water, not latrine breaks for the last 24 hours. Colonel Stewart kept the morale and order of his comrades, saying that the Japanese would for sure not abandon them. At night, they decided to try and pry open the hatch after one prisoner produced a butcher’s knife.

Unnecessary Death

Everyone tried to get up the ladder in panic, but the officers managed to bring back order. Soon, the men were climbing one by one, but little did they know that a machine gun fire was waiting for them as they tried to exit. After a while, the prisoners managed to stop the firing, and 1750 of them made it into the water. They were again met with gunfire as they tried to swim toward the Japanese boats. Some of them made it into the ship, while the others were shot and thrown back into the water.

Some POWs were picked up and brought to Shanghai, while 338 were rescued by Chinese fishermen who swam to save the prisoners. However, they were collected the next day as the Japanese landed on the Dongji island.

All in all, 846 men died trying to escape sinking with Lisbon Maru. Those who survived were brought into forced labor, and many of them died from the cold winter.

When the war ended, the captain of Lisbon Maru was sentenced to seven years in prison, and the Japanese interpreter was sentenced to 15 years, but Lieutenant Wada, who ordered to close the hatch, was not punished as he died before the trial.

This sinking was not a tragic accident but a case of clear criminal negligence on the part of the Japanese.  A ship loaded with POWs should have had “POW’ painted on its sides which would have kept any US submarine or aircraft from attacking it.  The ship should have had her lights on at night with the POW sign illuminated. The Japanese authorities could have also sent an uncoded radio message to the Allies that Lisbon Maru was sailing on a certain date, bound for a certain port on a certain course, and was carrying Allied prisoners. This too would have prevented her from being sunk or attacked.

When the Japanese loaded troops on board beyond just the prisoner guards, they made the ship a legitimate military target regardless of the presence of prisoners on board. That was a clear and deliberate violation of the Geneva Accords. Japan did sign the Geneva Convention but, failed to ratify it, so was not bound by it specifically. but in 1942 Japan made a promise to abide by its terms and indicated it would observe the Hague Convention of 1907 which also had previsions regarding the treatment of POWs.  No doubt Japan did this to assure the protection of its own troops and civilians that fell into Allied hands knowing full well that they had no intention of doing so themselves.

Following WWII the Japanese officers tried(and hung) for war crimes were charged almost exclusively with crimes against defenseless civilians and POWs in their care. The number of crimes was massive resulting in 5,600 individuals being tried by 11 countries in 2,200 cases in 51 locations around the Pacific. More than 1,100 death sentences were handed down by judges.