That merging of the past and present may encourage thoughts of how the film relates to today — even outside the subject of war.
Brexit doesn't involve MPs kitting up to go to battle and neither are their lives on the line. But there is a political crisis and a sense that the future of the country is in the balance.
The conflict within the Conservative Party over Brexit is often referred to as a political civil war and it is very close to having major consequences for Britain.
The structure of Jackson's film — essentially in three parts — is reminiscent of what has happened with Brexit.
The documentary begins with teens as young as 15 being lured into war. The film then covers the grim reality of the conflict, and finally the aftermath for survivors.
It spends quite a bit of time on the various reasons why young men volunteered for battle, with many lying about their ages to sign up. Included were emotional button-pushes such as 'for their country' and the desire for adventure.
Brexit always had emotional power as an idea, as a lure, before the 2016 referendum.
The Leave side's idea that Britons would 'take back' their country, with their own rules and enforced borders had appeal for many and was easy to grasp. It was presented as a straightforward change.
The Remain side had more complex, dry arguments about why it was better to stay in the community of the European Union, for security, the economy, for younger voters' futures.
Key Brexit believers played on simplicity before the referendum — won by Leave over Remain by 52 to 48 per cent. That continued well into the post-vote period.
In April 2016 Michael Gove, now Environment Secretary, said: "We hold all the cards and we can choose the path we want". In October of that year former Brexit Secretary David Davis said: "There will be no downside to Brexit, only a considerable upside".
Trade Secretary Liam Fox said in July last year that getting a free trade deal with the EU should be "one of the easiest in human history".
Just as the soldiers shipped abroad to fight Germans were forced to adjust their expectations to the reality of dead mates, rats, lice and shell-fire; so too has it become apparent how much more difficult and complicated Brexit is than what it was sold as.
Whereas the soldiers had to accept the reality of their situation to try and survive it, in their current stand-off with Prime Minister Theresa May, at least some Brexiteers have clung to their fantasy ideal in opting to resign. Others are reportedly wanting to make changes to the UK-EU plan from the inside of Cabinet.
Whereas soldiers came to have a realistic view of their opponents on the battlefield, there is little common ground and much angst over Brexit. No side really gets what they want with May's negotiated plan.
As with the war, Brexit has felt for a long time like a situation stuck knee-deep in the muddy trenches.
There is apparently no escape from the set path, even as public opinion has changed from mid-2016.
A YouGov poll at the weekend had Remain at 54 per cent over Leave at 46 per cent.
Should Tory MPs force a vote and dump May as leader or later help vote down her plan, the end result would most likely be a 'no-deal' Brexit. Britain would crash out of the EU into instant financial, customs and transport chaos.
The PM has hinted that there could be no Brexit at all but that is most likely a scare tactic to get unhappy troops to accept the Brexit she's offering. Yet considering the possible shocks ahead, a second referendum is a valid option.
May is hoping that by the time MPs vote in Parliament on December 20 they will at least see her plan as the least-worst option.
For many of the soldiers, going home didn't turn out the way they expected.
For British voters, Brexit could turn out to be a costly experiment.
