What Nolan aims to do with Dunkirk, if I interpret it correctly, is to make us feel what it was like to actually have been there, as an anonymous soldier, one of countless thousands. And as is clear near the end, the operation at Dunkirk is seen as a military disaster and the soldiers were burdened with a feeling of shame for letting down their country. Nolan dedicates this film to them and to their experiences.
For him the best way to do this is to simply chronicle the event from a couple of viewpoints, without ever giving us proper characters to identify with. There are no real characters in this film, because viewers are supposed to be characters themselves. To identify with a character is one more step of removal that Nolan wanted to short-circuit. We are just observers as if we are running along. I would almost say that the film is akin to a computer game where you yourself fill in the blank space of the observer, with the major difference that Dunkirk is a traumatic experience that happens to you.
And the hopeless situation at Dunkirk is the great traumatic experience where the other soldiers around you feel just as helpless as you do to influence what happens. Nolan’s deceptively simple plot of a couple of soldiers trying to find a boat to escape that horrible beach does the trick. Every time they think they made it, they find themselves in another situation that strands them back at Dunkirk. Boats are full. Or they are bombed, or some other disaster happens. Or a pilot finds himself rescued and then taken back to Dunkirk. The sheer helplessness and desperation is the emotional goal of the movie. That is how their memories are honored.
I find the script to be extraordinarily successful in this. We are a young eager man on a fishing boat, steering towards Dunkirk. We are an exhausted soldier sitting in the sandy wind and salty, murky waters of the North Sea. We see what it feels like to chase planes far above the waters.
Compared to Nolan’s earlier films, Dunkirk feels refreshingly simple and streamlined in its message. No convoluted science fiction story to make rather basic points about love. Simple empathy for the soldier in battle is enough, and do away with strict black and white opinions about courage. Nolan tries to depict bravery in impossible situations, and addresses shellshock and painful choices between life and death, mercy and toughness. For instance, when the character George on the boat asks if a rescued soldier is a coward, Mr. Dawson (Mark Rylance) corrects him, and later on we see his son set aside his own anger to spare that soldier more emotional pain.
On top of all that, yes, it is technically impressive and visually overwhelming. The lack of characters can turn one away from the film, but it is hard to mark it as a fault when it was intentionally done. It might work for you or it might not. But, if there is one thing that Christopher Nolan never lacks, it is the ambition to tell grand stories. He has the freedom and the guts to follow his own vision, and I admire him for that. So, Dunkirk is admirable and impressive, once you stand back to consider what Nolan’s point was with it and what he did with it.