Was Dundirk the turn around in WW2? Why was Hitler backing his troops and hold them back for 2 days? I thought it was because he was fighting against his own generals. Source: Adolf Hitler Biografie Peter Longuich. (Really good book dunno if it's available in other languages then German.)
I'm providing links to previous discussions just for convenience. This is not to discourage further questions and debate -- please feel free to raise any other points that you like to.
I do find "Why did Hitler not crush the British army when he had it surrounded and cut off at Dunkirk?" at https://www.reddit.com/r/AskHistorians/comments/6lds2b/why_did_hitler_not_crush_the_british_army_when_he/djtaq0b/ , a reply by /u/threechance . The massive thread under it has a link to
"Do most contemporary historians agree on the reason for the halt order at Dunkirk?" at https://www.reddit.com/r/AskHistorians/comments/4eqt6c/do_most_contemporary_historians_agree_on_the/ , replies by /u/PantsTime and Heimdall2061 .
Another angle is in "Was the Dunkirk evacuation a triumph or defeat for Britain?" at https://www.reddit.com/r/AskHistorians/comments/2nl7ln/was_the_dunkirk_evacuation_a_triumph_or_defeat/cmepl7t/ , with replies by coinsinmyrocket and CrossyNZ. This was the only FAQ item that I could find, which astonished me.
You can also see "why dident the Nazis fight the 400,000 stranded Brits in Dunkirk?", with vonadler's answer, at https://www.reddit.com/r/AskHistorians/comments/6kfmhk/why_dident_the_nazis_fight_the_400000_stranded/
If you want much more reading about Dunkirk, at the time of the movie Dunkirk there was a megathread.
Edit for one-stop shopping: /u/coinsinmyrocket was the speaker on an AskHistorians podcast that covered this topic as well: https://www.reddit.com/r/AskHistorians/comments/8bzeut/the_askhistorians_podcast_109_dunkirk_the_dawn_of/
/u/scarlet_sage did a good job posting some responses to this question from myself and other flairs. There was also a recent AskHistorians podcast that covered this topic as well.