New Zealand director Peter Jackson had long wanted to make a film about WWI. As a child, Jackson's father often told him of his grandfather's war stories during the war, stories which fascinated him then and continue to fascinate him to this day. To that end, Jackson dedicated They Shall Not Grow Old to his grandfather, who Jackson said that he understood more of what "would have gone through" in the war after making the film.
Jackson was commissioned to make the film in 2015 by 14-18 NOW (the UK's art program for WWI) and the Imperial War Museum (IWR). After they requested footage from the BBC and the IWR to craft the documentary with, the BBC provided over 600 hours worth of interviews and the IWM provided over 100 hours of original footage from WWI. Jackson and his teamed ended up developing groundbreaking technology to craft the film. Although they didn't have the budget to fully colorize all of the footage, the team restored all of the footage the IWR gave them - including making the images clearer and increasing the FPS of all the footage (in WWI, all of the movie cameras were hand-cranked, which made films of that era move at an inconsistent pace, making the movements of those involved in the film seem strange and robot-like).
Early on in the process, Jackson decided that the film wouldn't feature a traditional narrator. Instead, the film would be told by the soldiers who fought the war themselves - all of which was mined from the interviews the BBC provided him.
Jackson summed up the film well: "This is not a story of the First World War, it is not a historical story, it may not even be entirely accurate but it's the memories of the men who fought – they're just giving their impressions of what it was like to be a soldier."
