Peter Jackson, From ‘Lord of the Rings’ to the Trenches of World War l

For his new World War l documentary, “They Shall Not Grow Old,” director Peter Jackson was adamant the soldiers should tell their own stories.

Director Peter Jackson at the premiere of New Line Cinema, MGM Pictures And Warner Bros. Pictures "The Hobbit: The Battle Of The Five Armies" at Dolby Theatre on Dec. 9, 2014, in Hollywood, Calif. Frazer Harrison/Getty Images

To do that, the acclaimed New Zealand director hired forensic lip readers to go through old silent film footage of the war and uncover the conversations that took place in the trenches and on the battleground 100 years ago.

Those words were mixed with interviews with former soldiers from 600 hours of tape in the BBC archives, to create a documentary that includes only the words of the soldiers themselves, in a full-color war as they would have seen it.

“There have been lots of documentaries made on the First World War ... and I just decided for this one to strictly just use the voices of the guys that fought there,” Jackson, director of the “Hobbit” and the “Lord of the Rings” series told Reuters onTuesday, Oct. 9. “So no historians, no narration, no nothing.”

Soldiers in the trenches, World War I footage. Screenshot/ WingNut Films/Peter Jackson/Reuters

Old film was meticulously restored. Computers were used, not only to add color to black and white footage but to remove imperfections, fill splices, and reconstruct missing frames from a film that was shot with fewer frames per second than today.

Forensic lip readers, who usually work with the police determining what people say on silent security camera footage, were able to decipher the words spoken long ago.

Actors were hired to give the soldiers an on screen voice. The film will have its world premiere at the 2018 BFI London Film Festival from Oct. 10 to Oct. 21.

“It’s not the story of the war,” said Jackson. “It’s the story of the human experience of fighting in the war.”