The 828 Unforgotten, a documentary revealing the tragic truth behind the sinking of the Lisbon Maru, a Japanese transport ship carrying over 1,800 British prisoners of war (POWs) in 1942, is expected to be released in early 2020. 

Back in 1942 during World War II, the ship Lisbon Maru was torpedoed by The Grouper, a US Navy submarine, and soon sank about 3 nautical miles from Dongji Island, Zhoushan, East China's Zhejiang province.

Fishermen from the island risked their lives to rescue the British soldiers who fought their way out of the ship, but only managed to save 384 of them, with 828 sinking with the ship, drowning in the sea or shot dead by the Japanese troops. 

The fishermen took the rescued British soldiers to their homes and gave them clothes and food.

"I still remember the piece of turnip that a local fisherman gave me. It is the best food I've ever had in my life. The fishermen risked their lives to save us. They are the real heroes," said William Benningfield, one of the 384 rescued soldiers.

However, the trauma caused by the tragedy has never healed. 

"Christmas Day is still not a good day for him (Benningfield). He would sit quite often, or else he'd get drunk," said Benningfield's elder son. The British soldiers surrendered to Japanese troops at Christmas in 1941.

"If the tragedy didn't happen, there would have been 828 more happy families right now," said Fang Li, the producer of the documentary, who heard the story from Dongji fishermen and decided to uncover the truth behind the tragedy.

Fang started to film the documentary in April and published full-page advertisements in three major British newspapers – The Times, The Daily Telegraph and The Guardian – in July to look for relatives of Lisbon Maru POWs. More than 300 families have so far been reached.

"I can't imagine that so many young lives were buried under the water beneath my feet. They were almost the same age as my son, but they died. I just can't let it go," said Fang.

The film crew led by Fang has done investigation in many places in Britain, Canada, Japan and France for the documentary.

"It is a story similar to the Titanic and Dunkirk. Many things can be revealed from the documentary, such as the human panic in struggling for survival, the heroism, the modern reflection on the war, and the cultural conflicts between different peoples in their attitudes toward the war," said Fan Ming, director of the documentary.