Note: some of these are based on novels. That really doesn't make it different or better, because the jeu d'esprit aspect to these sequences doesn't go away. By which I mean that the director appears to think he has a vocation from something-or-other to insert gratuitously gory scenes in war films to educate us, but it feels like a gleeful exercise in degradation instead, a Lucanian glory in the abject.
The benchmark for this is, of course, Saving Private Ryan. Did you know that advancing from the sea into massed German machine gun fire makes for simply amazing exit wounds? Well, you do now! Does it affect the rest of the movie at all? No? Too bad. Tom Hanks must teach you that D-Day wasn't all fun and games.
Next up: Pearl Harbor. What, the eponymous attack is unrelated to the rest of the movie? How is that even possible? I don't know either. But it is! No one you care about is killed in the attack, which is astonishing, because it's Pearl Harbor! Somehow, though, it manages to be a violent but almost inconsequential fulcrum for the rest of the asinine plot, because who cares about thousands of faceless sailors when you can have sex in an airplane hangar.
The evacuation of Dunkirk wasn't, strictly speaking, a battle, but Atonement is also stupid. It is so sad that James McAvoy is dying of sepsis, and the tragic plight of the BEF is simply a metaphor for this, or maybe the other way 'round, or maybe I just don't understand brilliant, affecting film-making, or the larger issues at work, or the scope of human tragedy. That's probably it.
Our final example is Birdsong, a sweeping Great War drama about some moron's romantical problems and obsession with playing cards. The director gives us an extended Somme sequence. Did you know that advancing uphill into massed German machine gun fire makes for simply amazing exit wounds? Well, you do now! Does it affect the rest of the movie at all? No? Too bad. Eddie Redmayne must teach you that he left his heart in Amiens and he knows the terrain and he is the only man in the entire British Army with an elementary moral sense.
No, it is not my fault that I failed to find these things affecting. I'm the girl who cries immediately when someone writes, "The Devonshires held this trench. The Devonshires hold it still." I am predisposed to disintegrate into helpless tears at stuff like this. If I don't care, because you haven't bothered--even the littlest bit--to make me, you have failed.
They don't help the story-telling. Sure, they give the make-up department something to do, and maybe for really stupid spectators they provide the valuable lesson that war is bloody and terrible. Well, thanks.