23 May 1940
The German II Panzer Division launches a determined attack on Boulogne. The defenders hold out, but the British decide to evacuate their troops. 3,060 men are evacuated on 23 May.
British troops based at Calais attempt to link up with the forces at Dunkirk, but their progress is blocked by strong German forces.
Oswald Mosley, British fascist leader arrested
The War at Sea, 1939-1945, Volume I: The Defensive, S. W. Roskill
. This first volume in the British official history of the war at sea covers the period from the outbreak of the war through to the first British disasters in the Pacific in December 1941. Amongst other topics it covers the Norwegian campaign, the evacuation from Dunkirk and the first two years of the Battle of the Atlantic. The text is meticulously researched, and is rooted in a detailed study of wartime records, both British and German. [see more
How to cite this article: Rickard, J (28 December 2007), 23 May 1940, http://www.historyofwar.org/secondworldwar/date/1940_05_23.html