Screenplay writers are pretty good at filling story gaps.

My wife hated Dunkirk (she's not high on war movies anyway) but she is in no way knowledgeable about WWII other than "We won, they lost." I thought it was seriously flawed as most of those who saw it had no idea what was going on or why. I did, but I still didn't like it much more than my wife. Ask anyone under, say, 60 about Dunkirk, and about all you will see on their faces is puzzlement.