While doing some work tonight, I had on Michael Powell and Emeric Pressburger's wonderful (but I have the feeling somehow overlooked) 1941 film 49th Parallel.
The basic plot involves the survivors of a German U-Boat crew trying to make their way across Canada to the (at that point officially neutral) US.
There are many powerful moments in the film, one involving Anton Walbrook as the leader of a Hutterite community who responds to the fanatical Nazism of the naval lieutenant (played with remarkably convincing menace by Eric Portman).
Leslie Howard also has a key role in the film (as an author, canoeist and Thomas Mann fan...and a surprisingly good shot with a pistol), and I learned something looking at his Wikipedia page that I didn't know: he died in 1943 after being shot down on a flight from Lisbon to Bristol.
Several exhaustively detailed books such as Bloody Biscay: The Story of the Luftwaffe's Only Long Range Maritime Fighter Unit, V Gruppe/Kampfgeschwader 40, and Its Adversaries 1942-1944 (2001 by Chris Goss) by (which comes to a slightly different conclusion), Flight 777 (1957 by Ian Colvin), and In Search of My Father: A Portrait of Leslie Howard (1984 by Ronald Howard, Leslie's son), conclude that the Germans were almost certainly out to shoot down the plane in order to kill Howard himself. His intelligence-gathering activities (while ostensibly on "entertainer goodwill" tours), as well as the chance to demoralise Britain with the loss of one of its most outspokenly patriotic figures, were behind the Luftwaffe (German air-force) attack. Ronald Howard's book, in particular, explores in great detail written German orders to the Ju-88 Staffel (squadron) based in France assigned to intercept the aircraft, as well as communiqués on the British side which verify intelligence reports of the time indicating a deliberate attack on Howard.
I did not know that.