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Western Europe 1939-1945: Invasion

How worried was Britain about invasion 1940-41?

British government plans relating to a possible invasion, March 1941

Catalogue ref: INF 1/887

Government plans in case of invasion; INF 1/887 Government plans in case of invasion; INF 1/887

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What is this source?

This source is a letter from one senior official to another inside the British government in March 1941.


The letter is very useful as it is a response by the War Office to a letter from a different department. Norman Brook originally asked for estimates as to how much warning Britain would have if Germany did invade.

What’s the background to this source?

In May 1940 German forces drove British armies out of France. France surrendered on June 21st 1940. Nazi leader Adolf Hitler expected Britain to ask for peace terms soon after this but to his surprise British Prime Minister Winston Churchill refused. As a result, Hitler ordered his commanders to prepare for an invasion of Britain. The threat of invasion hung over Britain for some time.


Historians are divided about whether a German invasion could ever have succeeded. In the end, it never happened but this source gives some indication that the British government seriously considered that there might be an invasion, even as late as March 1941.

It’s worth knowing that...

Even if German forces had landed, the government had made detailed plans for resistance. The government liked to create a popular image of the British muddling through, but in reality the war effort was highly organised.


Despite this, the threat of invasion was strong in people’s minds. It never really went away until Hitler invaded the USSR in June 1941 and the invasion forces moved to the East.

What level of alert should Britain be on?

  1. In terms of warning people about invasion:
    • What was the good news in terms of German preparations?
    • What was the bad news?
  2. What did the chiefs-of-staff want people in the invasion areas to do and when?
  3. What level of alert would you put Britain on as a result of studying this evidence?

Record your answer in your threat level table you can always change your mind as you study other sources.