The BEF and Dunkirk, 1939-40
1. At first, Britain could not hope to help Poland, so far away, so the government was forced to prepare at home as best it could, and wait until Hitler attacked - this period of no fighting was called the 'Phoney War'.
2. When Hitler attacked, the British Expeditionary Force in France and the French were utterly unable to resist Hitler's 'Blitzkrieg' tactics.
3. How valid are newsreels of Dunkirk from the time? - by concentrating on small craft heroically taking soldiers from beaches, and the 345,000 troops evacuated, the government succeeded in presenting Dunkirk in the media as a wonderful salvation and example of British determination and team-work ('the myth of Dunkirk'), but really it was the HUGE defeat.