At 12.54 AM, U-9 torpedoes German steamer Sigurd Faulbaum (captured by Belgium on May 10) while under tow by 2 tugboats, 15 miles northeast of Zeebrugge. The stern sinks but the crew is rescued from the floating forepart by one of the tugs. http://www.uboat.net/allies/merchants/ships/322.html
2nd Panzer Division attacks Boulogne, triggering the evacuation of British 20th Guards Brigade which has just arrived. Several British and French destroyers are bombed until RAF fighters arrive at 7.20 PM. However, Germans are so close that tank shells and small arms fire claim several lives on the ships, including the captains of HMS Keith and HMS Vimy. 4,360 troops are rescued (naval losses; 61 dead, 62 wounded). http://www.historyofwar.org/articles/battles_boulogne_1940.html
Further North, British 3rd Royal Tank Regiment (equipped with cruiser tanks) and the 30th Motor Brigade land at Calais and hold off probing attacks by the 1st Panzer Division.
General Lord Gort withdraws British Expeditionary Force from Arras, where they had previously stopped Rommel’s Panzers.