In France, Belgium, Britain and the Netherlands, the war only really began following the invasion of Poland. For several months, the "strange old" war took hold.». Aside for a single day of French military operations in the Sarre on 16 September 1940, the German army did not move on the Western front. The Allied forces suffered from psychological exhaustion and low morale. However, on 10 May 1940, the German Army launched a major offensive against the Netherlands, Belgium and France. This was the beginning of the French campaign.
On 14 May, the main Dutch military strength surrendered, and on 17 May the last soldiers returned to the Netherlands, which surrendered. The Royal Family sought exile in Britain. Faced with greater resistance in Belgium, thanks to the support of British and French troops, Belgium surrendered on 28 May. Here also the Royal Family sought exile in England.
France was overcome in just six weeks. Unable to stop the German advance, the French and British armies had to retreat after 28 May, some 300,000 were evacuated within the space of 6 days towards England in Operation Dynamo in Dunkirk. The French government surrendered on 22 May.