The Battle of Dunkirk

There was never a plan to knock out the Dunkirk pocket. The Germans could have rolled up the Sand Dune area at Bray Dunes but they were held back by the French as the final divisions of the German army got away. So all my research was aimed at why was it and how was it, how did these formations get away? It was very, very close. If the Germans could have got these guys we would have been in serious trouble. They could have been hostages for negotiations, so on and so forth. I thought how on earth did they allow them to get away and so that's what was driving the research.