Frenchman Marcus Detrez was leafing through an album of photos depicting his grandfather's fulfilling life in Shanghai in the 1930s when a picture thrust him into appalling moments of war.

A sharp contrast to scenes of tranquil lakes and bustling food stalls on the streetside, the photograph shows a civilian, whose head has been completely blown off, lying on the ground.

The chance discovery made in the garage of his family home in 2021 put the 26-year-old on a truth-seeking journey that offered further evidence of the wartime atrocities committed by Japanese soldiers during China's War of Resistance Against Japanese Aggression (1931-45), as well as the resilience of local residents — which is all documented in a collection of 622 photographs.

Detrez, accompanied by two friends, arrived in Beijing on Saturday to donate the photos to China. They also plan to visit Shanghai to see venues shown in the pictures.

"I was very shocked when seeing the horrible pictures of the war with corpses and bombings. My mom told me the story of my grandfather, his life in Shanghai, his struggles, the Japanese invasion and the war crimes he witnessed," Detrez said during an interview with China Daily on Tuesday.

Detrez has spent his spare time researching the topic and attempting to learn more about his grandfather's experiences in Shanghai as a business owner and a witness of and fighter against the brutalities of war.

The first group of pictures uncovered by Detrez in the garage totaled about 170. In December, he and his family members found hundreds more related pictures.

"We've been discussing what we should do with these pictures, and finally we decided to donate them to China," he said.

The pictures are now stored in a leather, handheld briefcase — the same one that his grandfather used when traveling back from China many decades ago.

As he opened the suitcase and sorted through the pictures in waterproof covers and envelopes, Detrez appeared unfazed by some of the graphic, bloody images.

But he said he has had many sleepless nights since finding these pictures, and his senior family members have been traumatized for many years by the memories.

"We've been carrying a heavy (emotional) burden," said Bastien Ratat, one of Detrez's friends assisting with the donation.

But they have persisted, driven by a desire to spread awareness about the truth of a part of history that they believe is not fully understood by the world.

Ratat, who is also from France, explained that in his home country and many parts of the world, China's War of Resistance Against Japanese Aggression is known as the Sino-Japanese war.

"There is a big difference because it was a war where the Chinese people were under attack, and resisted and defended themselves," he said. "For Detrez's grandfather, a foreigner in Shanghai, his world had suddenly changed and he had to be resilient to protect his family and his friends, including Chinese friends."

Despite the fact that looking at these pictures is a painful experience, Detrez said it is important to confront and reflect on such historical events.

"As human beings, we have made some mistakes, and we should make sure that we learn from that," he said. "I hope that we can tell the truth and inspire the future generations. If we don't tell the truth, if we deny the truth, we just go into a big war."

After finishing his trip in China, Detrez, a language teacher, said he plans to establish an association in France to promote awareness about the wartime atrocities suffered by the Chinese people and foster people-to-people friendship between China and France.

Contact the writers at wangxiaoyu@chinadaily.com.cn