As the movie world erupts in loud applause for Dunkirk (2017) there is a serious question being overlooked. A defining characteristic of historical drama is that it leaves us with a better understanding of history. If a viewer knew nothing of the history of Dunkirk would this film make sense? In other words, does this film have a coherent narrative that explains what happened or is it a digital effects spectacular?

Dunkirk depicts three dramatised military scenarios that unfold in the air, on the ground, and at sea. Viewers must draw on prior knowledge to make sense of why 400,000 mostly British troops became trapped on a French coastline surrounded by German forces and facing imminent annihilation. The only hope to save what Churchill had called "the whole root and core and brain of the British Army" was to evacuate the troops across the English Channel. From fragments of talk between officers we gather that British Forces were unable to provide effective air support and troop-carrying vessels, so a hastily arranged flotilla of 800 British fishing boats and pleasure craft are sailing towards Dunkirk to save whoever they can carry. The action shifts frequently between parallel and sequential timeframes: in one scene, the camera is running along a beach, the next flying in a Spitfire sortie, then on top of or under a sinking ship. There are no prominent protagonists or antagonists, just archetypes of military and civilian personnel, both heroic and not. We follow a couple of young soldiers fleeing for their lives while enemy bombings and gunfire tear into their comrades. We meet a British civilian skipper who has answered the evacuation call and follow his journey across the channel to rescue soldiers from bombed ships and downed planes. We share the cockpit of a lone British fighter pilot as he fires on enemy planes to stop them bombing British troops on the beaches and on vessels, all while knowing that he is running out of fuel.

What happens in each of the film's fictional scenarios is not the point: it is the totality of chaos and the scale of relentless carnage that assaults audience senses. When seen in high resolution 70mm film the spectacle is overwhelming. The booming soundtrack is repetitive and manipulative; constant percussive pulses and orchestral strings designed for only one purpose: to increase audience heart-rate. The dialogue is minimalist and voice recording quality in several scenes is poor but the action is all that matters. The scale of the combat scenes is massive and there are numerous scenes where the viewer will be disorientated, not knowing the good guys from the bad. But this is a pale imitation of what it must feel like in the chaos of battle.

This is hardly entertainment. If the director's intention is to numb viewer's senses with a 106- minute glimpse of hell then this film is a success. If it is to tell the story of Dunkirk, it just does not have the narrative framework to explain how and why one of the world's biggest military disasters even happened. If it is to commemorate the Battle of Dunkirk, then turning the story into a massive digital effects spectacle makes a limited contribution to our collective memory of what has been described as the crucial turning point of World War II. Where it fails to illuminate Dunkirk history it makes up for as an immersive masterpiece of spectacle.