BEF commander General Viscount Gort immediately saw evacuation across the Channel as the best course of action, and began planning a withdrawal to Dunkirk, the closest good port.

This gave Allied forces time to construct defensive works and pull back large numbers of troops to fight the Battle of Dunkirk.

"[9] In September 1939, after Germany invaded Poland, the United Kingdom sent the British Expeditionary Force (BEF) to aid in the defence of France, landing at Cherbourg, Nantes, and Saint-Nazaire.

This line had been designed to deter a German invasion across the Franco-German border and funnel an attack into Belgium, which could then be met by the best divisions of the French Army.

[13][14] The area immediately to the north of the Maginot Line was covered by the heavily wooded Ardennes region,[15] which French General Philippe Pétain declared to be "impenetrable" as long as "special provisions" were taken.

[18][19] Manstein's plan suggested that panzer divisions should attack through the Ardennes, then establish bridgeheads on the Meuse River and rapidly drive to the English Channel.

[23] The BEF advanced from the Belgian border to positions along the River Dyle within Belgium, where they fought elements of Army Group B starting on 10 May.

[26] During a visit to Paris on 17 May, Prime Minister Winston Churchill was astonished to learn from Gamelin that the French had committed all their troops to the ongoing engagements and had no strategic reserves.

Gort immediately saw that evacuation across the Channel was the best course of action, and began planning a withdrawal to Dunkirk, the closest location with good port facilities.

[30] After continued engagements and a failed Allied attempt on 21 May at Arras to cut through the German spearhead,[31] the BEF was trapped, along with the remains of the Belgian forces and the three French armies, in an area along the coast of northern France and Belgium.

Overwhelmed by what he later described as "a somewhat alarming movement towards Dunkirk by both officers and men", due to a shortage of food and water, he had to send many along without thoroughly checking their credentials.

[32] The engineers of the 2nd Panzer Division under Generalmajor Rudolf Veiel built five bridges over the Canal Line and only one British battalion barred the way to Dunkirk.

[42] On 23 May, at the suggestion of Fourth Army commander Generalfeldmarschall Günther von Kluge, Rundstedt had ordered the panzer units to halt, concerned about the vulnerability of his flanks and the question of supply to his forward troops.

It was picked up by the Royal Air Force (RAF) Y service intelligence network at 12:42: "By order of the Fuhrer ... attack north-west of Arras is to be limited to the general line Lens–Bethune–Aire–St Omer–Gravelines.

[62][page needed] The retreat was undertaken amid chaotic conditions, with abandoned vehicles blocking the roads and a flood of refugees heading in the opposite direction.

A special service attended by King George VI was held in Westminster Abbey on 26 May, which was declared a national day of prayer.

[29] Initial plans called for the recovery of 45,000 men from the BEF within two days, at which time German troops were expected to block further evacuation.

As a result, many British soldiers bitterly accused the airmen of doing nothing to help, reportedly leading to some army troops accosting and insulting RAF personnel once they returned to England.

[78] Remnants of the French First Army, surrounded at Lille, fought off seven German divisions, several of them armoured, until 31 May, when the remaining 35,000 soldiers were forced to surrender after running out of food and ammunition.

The paddle steamer HMS Crested Eagle suffered a direct hit, caught fire, and sank with severe casualties.

[86] With the docks in the harbour rendered unusable by German air attacks, senior naval officer Captain (later Admiral) William Tennant initially ordered men to be evacuated from the beaches.

The shortest was Route Z, a distance of 39 nautical miles (72 km), but it entailed hugging the French coast and thus ships using it were subject to bombardment from on-shore batteries, particularly in daylight hours.

From hell to heaven was how the feeling was, you felt like a miracle had happened.The Royal Navy provided the anti-aircraft cruiser HMS Calcutta, 39 destroyers, and many other craft.

Admiral Ramsay arranged for around a thousand copies to be made of the required charts, had buoys laid around the Goodwin Sands and down to Dunkirk, and organised the flow of shipping.

[110] After the loss on 29 May of 19 British and French navy ships plus three of the larger requisitioned vessels, the Admiralty withdrew their eight best destroyers for the future defence of the country.

[110] The wide sand beaches meant that large vessels could not get anywhere near the shore, and even small craft had to stop about 100 yards (91 m) from the waterline and wait for the soldiers to wade out.

[117] In addition to ferrying out on boats, soldiers at De Panne and Bray-Dunes constructed improvised jetties by driving rows of abandoned vehicles onto the beach at low tide, anchoring them with sandbags, and connecting them with wooden walkways.

[123] The more than 100,000 French troops evacuated from Dunkirk were quickly and efficiently shuttled to camps in various parts of south-western England, where they were temporarily lodged before being repatriated.

"[a][130] Oberkommando der Wehrmacht (the German armed forces high command) announced the event as "the greatest annihilation battle of all time".

Another complaint was that German guards kicked over buckets of water that had been left at the roadside by French civilians, for the marching prisoners to drink.