Dunkirk. British & French fall back towards the coast, pressured by Panzer divisions (released from Hitler’s stop order) and bombed by Luftwaffe at Poperinge. 4 British divisions under General Alan Brook hold the Ypres-Comines canal (Battle of Wytschaete). The first 7,669 British troops are evacuated from Dunkirk harbour. Germans advance within 4 miles, bringing Dunkirk in artillery range.
British withdrawal uncovers the Belgian right flank and allows Reichenau's 6th Army to storm through. At 5 PM, King Leopold III of the Belgians appeals to the Germans for peace terms, with Belgian refugees crowded in a thin strip of land behind the collapsing line. Hitler’s reply at 10 PM, “unconditional surrender”.
3rd SS Panzer Totenkopf Division troops under Hauptsturmführer Fritz Knöchlein machinegun 97 British prisoners of war in the French village of Le Paradis. The only 2 survivors will later testify against Knöchlein, leading to his execution for war crimes in 1949. http://en.wikipedia.org/wiki/Le_Paradis_massacre
150 miles West of Cape Finisterre, Spain, U-37 sinks British SS Sheaf Mead (32 lives lost, 5 rescued and taken to Ireland) and scuttles Argentinian SS Uruguay (13 crew rescued and taken to Spain; a lifeboat with 15 others is never found).