"Oh oh bloody brilliant kind of thing like when fishermen and other civilians had to paddle your army home when hitler was driving them into the sea at Dunkirk was it wot bloody good show."
You really need to get an education mate.
A grasp of simple English for a start! Then you might be able to read and understand history (probably just the Primary School version).
Two minutes research would set you straight on the effect on an expeditionary force, of having both flanks (Belgium and France) collapse, leaving them exposed to a pincer movement by a much larger force.
Getting 350,000 men off the beaches under fire was the victory which ensured that the UK would not be invaded, and indirectly sealed Hitler's fate.