What disastrous retreat to Dunkirk and what army captured?
A retreat yes but not a disaster!
The Dunkirk evacuation, codenamed Operation Dynamo and also known as the Miracle of Dunkirk, or just Dunkirk, was the evacuation of more than 338,000 Allied soldiers during the Second World War from the beaches and harbour of Dunkirk, in the north of France, between 26 May and 4 June 1940.
For every seven soldiers who escaped through Dunkirk, one man became a prisoner of war. Not exactly "an entire army captured"!
The BEF lost 68,000 soldiers during the French campaign and had to abandon nearly all of its tanks, vehicles, and equipment. In his 4 June speech, Churchill also reminded the country that "we must be very careful not to assign to this deliverance the attributes of a victory. Wars are not won by evacuations."
Dunkirk evacuation - Wikipedia
PS; As noted above I posted something similar to this earlier quoting the wrong person!