Peter Jackson's landmark They Shall Not Grow Old tells the story of the men who fought in WWI - straight from the mouths of those who fought in it. Jackson and his team went through several hundred hours of BBC interviews to find audio excerpts that best fit the narrative of his film. That is: how soldiers live - and fight - during WWI.
In an early sequence in the film, for example, the soldiers featured in the film discuss their feelings about the conflict and whether they liked or disliked it. The men also discuss why they willingly joined the service, saying that they felt an obligation to their country and their friends - virtually all of whom went into the service to serve their country.
Another large aspect of the film is the daily life of the soldier. The film pays particular attention to what the soldiers ate daily, how they survived in the trenches (from mortar or gas attacks, or just plain bad conditions), and even how they went to the bathroom daily (and some of the trials and tribulations that went along with it).
Ultimately, They Shall Not Grow Old tells the story of the soldiers who fought in WWI from their perspectives.