A good film - but a few scenes missing for a classic

Rating: 7/10 (21 July 2017)

What Nolan has done with Dunkirk is create an outstanding piece of cinematography, with an interesting concept that works well (the three balanced time-lines taking place at a different pace, a week, a day and an hour). However, there are just a few things missing that prevent this from being a masterpiece.
The first is a simple graphical introduction with maps. I know the assumption is that most people know about Dunkirk (and being a British history teacher, obviously I know the story too), however for global audiences, there simply isn't the knowledge there to understand what is going on. For example, what year is this? What has happened in the war already (the invasion of Poland)? Why is the situation so desperate (because Germany has surrounded the allied forces and overrun the French defenses by going through the Ardennes forest in Belgium)? The USA has not yet entered the war (for American audiences), and nether have the Soviets. The French are about to surrender to Germany, leaving Britian alone to face the Germans. Dunkirks location in relation to England. All of this could have been explained with a short graphical introduction (like in enemy at the gates) of less than 2 minutes long. It wasn't, and therefore it simply looks like the British are running away without any explanation.
The second thing that is missing is the desperation of Dunkirk. By all accounts, the evacuation was generally pretty orderly. However, after the initial introductory scene, there is none of this on the beach in the second half of the film. When things should be getting more desperate (and there were many thousands of British soldiers who got left behind) during the second half, it seems like the Germans stop attacking the beach (except for one lone aircraft that gets shot down by Tom Hardy). This isn't true, and in the end Hitler does order his troops to move in when the air-force fails. Not to mention, the fact that many of the small boats get sunk too - it was an evacuation under fire, this is missing from the end of the movie when the boats turn up. It gives the impression that the evacuation was somehow fine once the boats turned up and does a disservice to the heroes on those boats and the whole first half of the movie (set on the mole - ignoring the parts at sea). This could have all been improved with a bit more artillery and plane attacks at the end of the movie.
The final scene which could have been included was Murphey's story - just a few scenes of his own evacuation from the beach - during the second third of the movie (increasing the fact that the mole was a week - whereas at the moment it seems it is two days, not a week), and then how he ended up being the sole survivor on his ship to be rescued - explaining why he is suffering PTSD would justify his earlier attack on the young boy. This would increase the length of the movie to about 2 hours and a bit - which is how long this movie should be. At the moment it is simply too short, and that prevents it being a masterpiece. Shame, because apart from that Nolan did a great job.