I was once privileged to own a DSM and bar, one of only 153 awarded during WW2. The medal was awarded to a rating who was placed in charge of a boat which was lowered from a warship, and which then made several return trips to the beach to rescue waiting troops, all the time under air attack. The bar was awarded for the unsuccessful attempted rescue of the 51st Highland Division at St Valery a week or so later, when the boat commanded by the same rating had to withdraw after coming under heavy fire from the cliffs overlooking the port.
Just two examples of hundreds of acts of heroism during the evacuation, many of which would have gone unwitnessed and unrecognised. Let's hope the film concentrates on them