On Oct 24, 1944, more Americans died in a single sinking than on any other ship in history. They weren't sailors. They were prisoners of war. And almost nobody remembers them. Arisan Maru was a brand new Japanese cargo ship, finished in the summer of 1944. She was built to carry freight, not people. On Oct 11, 1944, at Manila, the Japanese loaded 1,782 Allied prisoners into her cargo holds. Most were American soldiers, sailors and Marines. Many had survived the fall of Bataan and Corregidor in 1942, the Bataan Death March, and more than two years of starvation, disease and beatings in Japanese prison camps. There were civilians among them too. With American forces about to return to the Philippines, Japan was shipping prisoners north to be used as slave labor in Japan and China. The men called these vessels hellships. The holds were dark, airless steel boxes. The men were packed in so tightly that many couldn't lie down. The tropical heat was suffocating. There was almost no water or food, and buckets lowered from above served as toilets. Arisan Maru didn't even leave right away. With American planes raiding Manila, she sailed south and hid along the coast of Palawan for days, the prisoners baking in the holds the whole time. On Oct 20 she returned to Manila. On Oct 21 she finally sailed for good, joining a convoy headed north. Like other hellships, she carried no markings to show there were prisoners aboard. To American submarines, she looked like any other Japanese freighter. On the afternoon of Oct 24, Arisan Maru was in the Bashi Channel, between the Philippines and Taiwan. That's when an American submarine torpedoed her. The ship didn't sink right away. The Japanese crew and guards abandoned her, taking the lifeboats. They left the prisoners in the holds. The prisoners got out anyway. Almost every one of them climbed out of the holds and onto the deck. Some raided the ship's stores for food and water. Then the ship began to go down, and they went into the sea. Nearly 1,800 men were now in the water, clinging to wreckage. Japanese destroyers came back. They rescued Japanese survivors. They would not take the prisoners. Men who swam to the destroyers and tried to climb aboard were pushed back into the water. Then the destroyers left. Night fell. The men were weak from years of starvation and disease. One by one, they drowned. Of the 1,781 prisoners aboard, only nine survived. A few of them found an empty lifeboat drifting in the dark. With almost no supplies, they sailed it all the way to the coast of China, where Chinese civilians and guerrillas hid them from the Japanese and helped them get back to American lines. Others were picked up by the Japanese and spent the rest of the war as prisoners. The submarine that fired the torpedoes is usually believed to be USS Shark. That same day, Japanese destroyers hunted Shark down and sank her with all 87 men aboard. Her crew never knew who had been inside the ship they attacked. Arisan Maru was one of the worst disasters of a much larger horror. Across the war in the Pacific, around 20,000 Allied prisoners died aboard Japanese hellships, many of them killed by American torpedoes and bombs. The families of most of the men on Arisan Maru didn't learn what had happened to them until after the war. It remains the greatest loss of American life at sea in history.