The Dunkirk evacuation, codenamed Operation Dynamo and also known as the Miracle of Dunkirk, or just Dunkirk, was the evacuation of Allied soldiers during World War II from the beaches and harbour of Dunkirk, in the north of France, between 26 May and 4 June 1940. The operation commenced after large numbers of Belgian, British, and French troops were cut off and surrounded by German troops during the six-week Battle of France. In a speech to the House of Commons, British Prime Minister Winston Churchill called this "a colossal military disaster", saying "the whole root and core and brain of the British Army" had been stranded at Dunkirk and seemed about to perish or be captured. In his "We shall fight on the beaches" speech on 4 June, he hailed their rescue as a "miracle of deliverance".
After Nazi Germany invaded Poland in September 1939, France and the British Empire declared war on Germany and imposed an economic blockade. The British Expeditionary Force was sent to help defend France. After the Phoney War of October 1939 to April 1940, Germany invaded Belgium, the Netherlands, and France on 10 May 1940.