Why didn't Hitler round up the BEF at Dunkirk with Guderian's panzer?

Answer 1

The main reason, was that Göring asked Hitler to let the Luftwaffe (the German Air Force) giving the finishing stroke. Göring thought that the Luftwaffe would have been strong enough to, in the same time, fight the RAF, and to destroy the BEF at Dunkirk.
The others generals (Rommel and Guderian mostly) argued the fact that a combined assault would destroy the entire BEF (250 000 men), plus a part of the French army, and the last forces of the Belgian army : more than 1,000,000 men ! The casualties would have been not high (the Allied were exhausted, without efficient supply), and the German victory would have been total. The 4th of June, after the unsuccess of the air offensive, Hitler decided to attack Dunkirk with the Panzer, but 338,000 men could escaped, and were ready to defend England.
May be Hitler didn't want to damage too much the proud of England (he was hoping to sign the peace with England, and let the seas to the British).

Answer 2

Several theories:

1. It was still a big job, and the casualty to gain ratio might not have been appealing. Granted, the Soviets had no such qualms, but the Germans generally conserved their human resources at this point in the war.

At Dunkirk, the Brits had air power that could match the German air power, unlike other spots in Europe. And, at Dunkirk, the Brits were fighting for their national existence, not to defend France -- there is a big difference.

2. Hitler actually respected the Brits, and in many ways, wanted to be like the Brits. The Brits had an empire, and Hitler wanted an empire too. History is clear that Hitler regretted war with England. As quirky as it seems, I think that Hitler actually spared the BEF for that reason.

Answer 3

To add to what Geek has said.

(1) It is arguable that the rapid rush to the coast by the German forces had grossly extended their supply lines and they just could not have supported a continued fight.

(2) Hitler would have liked to have made peace with the UK at this time (see G's point 2) and perhaps done a deal whereby he would have had a free hand in Europe, leaving the British Empire intact. There was a peace element (Lord Halifax etc) in the British Government.

(3) Hitler was totally irrational in the way he fought battles. He was to busy swanning around Paris on holiday to push home his advantage after Dunkirk. See also his actions at the time of Stalingrad which led to the loss of a complete army.