Battle of Britain (1969). Tosh, but entertaining tosh, and for once a war film with hardly any Hitler. Big names in it too - Laurence Olivier (before the knighthood), Michael Caine, Ian MacShane, Robert Shaw, Christopher Plummer, Trevor Howard, Susannah York. Low-level brain power required but it does give a good insight into how close the Germans came to achieving the invasion of England.
One very good scene stood out to me: a load of German pilots sitting down to dinner, having taken pretty catastrophic losses recently. No dialogue, hardly any sound. Camera focusses on one empty chair, and his mate looks glumly at the chair too. End scene. Thought that was very well done.