Dunkirk evacuation (1940). In the early summer of 1940, when the British Expeditionary Force (BEF) was cut off from the bulk of the French armies by the German panzer drive which broke the French front and reached the Channel coast, FM Lord Gort began to consider a withdrawal to the coast. At the same time the War Office envisaged the evacuation of non-combatants and key specialists from the Channel ports. Preparations were entrusted to Vice Adm Ramsay, and the fact that a room in his headquarters below Dover castle had housed electrical generators may have persuaded his staff to christen the evacuation DYNAMO.
On 21 May preparations were increased to include large-scale evacuation, and on the 25th Gort made the courageous decision—for he was acting without political authority and in the face of French pressure to counter-attack—to evacuate from Dunkirk. The evacuation began on 26 May, and over the days that followed vessels of all sorts—including warships, passenger ferries, and privately owned ‘little ships’—took off troops from the east mole in Dunkirk itself and the open beaches to its north under fierce air attack.
In all 338, 000 men, 120, 000 of them French, were evacuated. Of the 693 British ships which took part, about 200 were sunk and as many again damaged, while RAF fighter Command, whose efforts were usually invisible to troops on the beaches, lost 106 aircraft. Churchill warned that ‘wars are not won by evacuation’, but Dunkirk was both psychologically and materially vital to the British war effort. Although the BEF had lost its equipment, it formed a nucleus of trained manpower, and its almost miraculous survival, as much a consequence of unseasonably fine weather and German errors as British gallantry, reinforced popular resolve. Many Frenchmen, however, were less enthusiastic about the operation, seeing it as evidence of British self-interest.
— Richard Holmes