I've only seen the trailers but it looks good. I knew of Dunkirk thru some old English films but never researched it.
But if you do look at the trailers, there is also some documentaries suggested on the subject and I watched a few.
What I got from it was that the German's view of warfare leaped ahead of the other countries. They didn't follow how the previous war went or their tactics. So Britain, France and Belgian presumed that Hitler would try to control areas that had been crucial in the past. Hitler on the other hand, (and the generals) instead looked to divide their forces and succeeded with the Bliztkreig. Several factors contributed to stall the victory that could have been Hitler's, if he had acted quickly. According to the documentary, Hitler had a small meltdown over the generals making plans to attack without his personal direction. The general in charge of the airforce wanted a bigger share in the fighting and convinced Hitler to let him attack instead of using the Panzers and the Army which would have made short work of them.
It is also interesting to find how propaganda was used on all sides, over Dunkirk.
For the British, it was a victory to have saved these men. One soldier that was interviewed, said that they were afraid of what the country would say once they got back. They thought they would be looked down on but instead they were called hero's. It was a victory to have snatched these men from death by navy and civilians, but it played down the fact that France was lost to the Germans and they had been routed.
For France, the British had betrayed them by retreating and leaving. To put the blame on the British meant that it wasn't their fault they fell to Hitler. Soldiers interviewed said that the government had told them they would win, so they were confident in their fighting. At first only the British soldiers were being evacuated because France did not want to appear like they were losing so they didn't put out an order to evacuate. It must have been terrible for them to watch the british leaving while they could only watch. At the end, out of all the soldiers evacuated, 1/3 of them were French soldiers. There was even German prisoners brought along which was surprising to me.
To the Germans, we are wining and we are great. No surprise there but, letting close to 300,000 soldiers get away isn't smart.
On the beach, soldiers wondered where their planes were and why they weren't they helping them. That was because most were in Britain to defend the country, but there were planes sent inland to slow down the germans. Two groups of soldiers also sacrificed themselves to hold off the germans. When they could no longer hold out after running out of ammo, they surrendered. One group was herded into a barn, grenades were thrown in and any that ran out, were shot. The other group had some that slipped away but the rest were captured.
As the 97 year old veteran said, you didn't need dialog to tell the story. I'm going to have to be in a certain mood to watch it because it is so visual.
Sorry for the long post on a movie I haven't seen yet. But I'm glad I watched the documentaries first, especially for the first hand accounts from the soldiers.