A historical documentary that shines a light on the fearless struggle of a guerrilla force that fought against Japanese invaders in Hong Kong in the early 1940s premiered in Shenzhen on Monday.

The documentary interviewed dozens of veterans of the Hong Kong Independent Battalion of the Dongjiang Column, which contributed greatly to China's whole-nation resistance war against Japanese aggression.

More than 200 guests, including the descendants of the battalion's soldiers, attended the documentary's premiere on Monday, the 92nd anniversary of the start of the War of Resistance Against Japanese Aggression (1931-45).

The battalion, led by the Communist Party of China, was established to protect Hong Kong after the city was occupied by Japan in 1941. It was made up of local workers, farmers, teachers, sailors, young students as well as compatriots from overseas.

Besides having hundreds of battles with the Japanese, the battalion also participated in rescuing over 800 notable Chinese figures and some allied soldiers out of Japanese-occupied Hong Kong. They also shared intelligence information with other anti-Japanese forces during wartime.

At Monday's event, Liu Shen, the documentary's director and screenwriter, said the production was conceived in and had been ongoing since 2009, and the team members have extensively visited war relics across Hong Kong. They filmed hundreds of hours of footage and collected thousands of historical photos.

Before filming the battalion's story, Liu also directed a few documentaries on that war, including one reflecting Hong Kong society under the occupation of the Japanese army from 1941 to 1945.

Deng Liping, the documentary's producer, and whose parents were both veterans of the battalion, said the purpose of the documentary is to help the young generations know that Hong Kong's prosperity is built on the elder generation's resistance against invaders. He said he hopes young people cherish the hard-won peace and make greater contributions to the city and the nation with their expertise and knowledge.

To commemorate their contributions, Hong Kong people built the Monuments for Martyrs Against Japanese Militarism in Wu Kau Tang, Tai Po and Sai Kung.

After Hong Kong returned to the motherland, the city placed a name list of the fighters of the Dongjiang Column in the memorial shrine at Hong Kong City Hall for the public to pay their respects.