Hi there -- while you wait for more answers, you may also be interested in these recent threads on Dunkirk:

https://www.reddit.com/r/AskHistorians/comments/6lds2b/why_did_hitler_not_crush_the_british_army_when_he/

https://www.reddit.com/r/AskHistorians/comments/6angfo/with_400000_available_men_how_were_the_french_and/

https://www.reddit.com/r/AskHistorians/comments/69z5y3/why_didnt_the_british_homefleet_rescue_soldiers/

https://www.reddit.com/r/AskHistorians/comments/69s7lh/in_a_til_post_someone_comments_that_the_british/

https://www.reddit.com/r/AskHistorians/comments/61ha2a/what_events_occurred_leading_up_to_the_evacuation/