Despite the fact that it never ended up happening, a Nazi invasion of England was kind of a common sense inevitability for a while during the beginning of World War 2. Had the Battle of Britain gone the other way, (or whatever alternate history conditions you prefer), a Nazi invasion across the channel was a real possibility.

Surely Britain had plans for what they would do, in that case? I can only imagine that they had numerous scenarios, depending on how the invasion went down. How did these plans match up to the German preparations? How much detail do we know about how the defense of Britain would have gone? What tactics did they plan on using, where did they anticipate the main battles to occur? Did the British commanders think they could successfully repulse a Nazi invasion of England, or were the plans geared more toward slowing them down and making it "not worth their while"?

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    Keep calm and carry on. Oct 10, 2014 at 21:29
  • I'm ashamed to say, I didn't even see that comment coming.
    – Nerrolken
    Oct 10, 2014 at 21:29
  • google.co.uk/… Oct 10, 2014 at 22:02
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    IF the Germans in summer/fall 1940 could have landed substantial forces AND been able to supply them, there wasn't much England could do. But even if the Royal Navy and RAF had stood idle and watched, this would have been a tall order for the German logistic system. Given the RN's forces in the area alone, the invasion could not succeed.
    – Oldcat
    Oct 10, 2014 at 22:13
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    We all know the story of Dunkirk, but left out is that due to the German focus on Paris and even the Blitzkrieg's inability to move fast enough, the British evacuated almost a million soldiers and their equipment along the coast of France. Far from be "understaffed" they had a HUGE force available to confront any invasion force the Germans landed. Consider how long it took the Allies to put a comparable number of equipped men in France with all the advantages they had. Germany did not attack because the landed men would have been doomed.
    – Roy
    Oct 4, 2015 at 6:29

4 Answers 4


The Wikipedia article is quite extensive, but the salient points are these:

  • The British army and militia were under-strength in 1940 but with exceptionally short supplies lines and tank production matching then eventually exceeding German production.
  • The British were perfectly willing to gas any invaders and had stockpiles prepared in advance (the British atomic bomb so to speak).
  • The south of England was converted into a battlefield with pillboxes and dragon's teeth to slow German forces and rake up causalities.
  • The Home Fleet, which was beefed up by recalling overseas assets and severely outnumbered the Kriegsmarine. Indeed the 1974 war game to extrapolate the outcome of a 1940 invasion of Britain resulted in a resounding loss to Germany due to the Home Fleet.
  • The population was educated in advance as to their role, to avoid a repeat of civilian paralysis that occurred in continental Europe when the Nazis did the unspeakable.
  • The British intelligence apparatus deceived the German high command as to Britain's capacity to repel invaders so as to encourage the German to misallocate resources or refrain entirely.

As T.E.D. mentions, the British high command would have fallen back to their Commonwealth allies such as Canada had the invasion been successful. In counter-factual history, the involvement of the USA and USSR would have been as vital as in real history.

If the invasion had gone ahead, the unused poster "Keep calm and carry on" would likely been have superseded by the planned slogan "You can always take one with you"

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    "You can always take one with you" -- wow, that is grim.
    – SPavel
    Feb 19, 2018 at 15:54

My comment above, as in pictures of thousands of pillboxes, was too flippant. Your question deserves a more serious answer.

There are two key things to consider, I think, when answering your question. One is that that the defence of the British Isles depended utterly on the Royal Navy. The Battle of Britain, considered pivotal in Britain's defence against invasion, was crucial because Germany could only even begin to contemplate a channel crossing if the all powerful Royal Navy could in part be neutralised by the Luftwaffe. And even then, in the case of absolute control of the air, most Germans still doubted they could overcome the Royal Navy and effect a successful invasion.

The second thing to remember, and here's where the pillboxes come in, is that Britain had just left most of its best equipment at Dunkirk. The cupboard was bare. Pillboxes were a quick and relatively easy way to establish a line of defences on the south coast.

I'm not sure whether anyone expected the pillboxes to work but they were a plan B, a very lowly plan B. Plan A was to stop the Germans in the channel, or dissuade them from the attempt, using sea power and air power. Which in fact is what happened.


Churchill always maintained publicly that, worst case, their government would retreat to its colonies (most likely Canada) and try to fight on from there. For example, there is this often overlooked coda to his Fight them on the beaches speech:

... and if, which I do not for a moment believe, this island or a large part of it were subjugated and starving, then our Empire beyond the seas, armed and guarded by the British Fleet, would carry on the struggle, until, in God's good time, the New World, with all its power and might, steps forth to the rescue and the liberation of the old.

However, he was likely telling the USA that at least partly for propaganda purposes. Many in the USA figured the UK would quit the war (eg: Ambassador Joseph Kennedy), and were against giving them any material support that was liable to go to waste with a soon-to-be non-combatant (or worse yet, end up in Nazi hands).

  • That's if England was successfully conquered. I'm wondering if there are plans (or if any plans have been publicly released) along the lines of "marine and armored units will counter-attack through Portsmouth, while reserves will hold a defensive line west of Dover. If they are overwhelmed, fall back to Rochester and regroup." Do we know how the invasion itself would have been handled, on the British side, the way we know about the German plans in that Wikipedia article I linked?
    – Nerrolken
    Oct 10, 2014 at 22:07
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    These kind of plans were complicated by the fact that the fragments of units evacuated from Dunkirk had lost a lot of equipment and transport, so would have had trouble moving about normally until the lack had been made up. By the time this had been done, the threat had dropped off. Certainly options were discussed, but first you need to know where the landings actually are.
    – Oldcat
    Oct 10, 2014 at 22:21
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    sorry, but you are talking about contingency if britain was conquered, but the question asks for defense plans.
    – user5001
    Oct 11, 2014 at 11:31

Basically, the issue was that if the German fleet could get the "first wave" across the Channel, would the Germans be able to reinforce/resupply adequately to defeat the British.

As William L. Shirer pointed out in "The Rise and Fall of the Third Reich," the German navy expected to lose every ship, in a cross-channel landing. That's both war- and transport- ships.

In that case, the Germans would have to be reinforced/resupplied by air, as at Crete. That would have been a tough, almost undoable job. So the main British defense plan would be aimed at preventing reinforcements/resupply, both across the English Channel initially, and subsequently in the air, through anti-aircraft fire. Also, British ships could bombard German land forces from the sea side, catching them in a cross-fire with land-based artillery.

It is interesting to note that (because of the rough weather in the English Channel), the Normandy invasion was given only a 50-50 chance of succeeding (and nearly called off). That's despite the fact that the Allies had complete air and naval superiority over the Channel, and "specialized" landing craft, the so-called LST's. The Germans had none of these advantages, meaning that their chances of success in a cross-channel invasion were less than 50-50.

  • Where does Shirer get his numbers? At one stage Kriegsmarine internally calculated a reserve necessary for 10% loss (mabye 2 optimistic), had things like en.wikipedia.org/wiki/Marinef%C3%A4hrprahm and the calculation 50-50 is and will remain just one estimate; so at best this number is sth of how an allied planner would later think it might have gone. In '40 RN reported once to Churchill that an invasion would probably succeed, at least that the RN could not stop that. In any case, this is a complete counter-perspective, estimating chance of success, and not for the British plans? Mar 27, 2021 at 17:05
  • @LаngLаngС: The model quoted by Shirer did not just assume one "crossing," but assumed that the German navy would continue to convoy supplies across the English Channel until it ceased to exist. Then the issue was, could the German navy "last" long enough for the Army to overrun the British Isles, or at least be "self-sustaining" with air support and "living off the land" only.
    – Tom Au
    Mar 27, 2021 at 17:40
  • @Tom Au What use is an offshore possession if all your ships are gone? But the other factor, no one has mentioned here is that had Hitler attempted such a bold venture, it would have tied down huge German resources over a long time period. And the USSR was rightly considered a more substantial threat to Germany, than Britain was - once France had fallen. This is clearly evidenced by the massive troop resources that were ultimately committed to the German eastern front.
    – WS2
    Jan 17, 2022 at 16:45
  • Anthony Eden (the then Foreign Secretary) described how on the morning of 22 Jun 1941, he was awoken by a knock on his door. Churchill's valet entered, "with a huge cigar on a silver salver" and said "Compliments of the Prime Minister - and by the way Hitler attacked Russia at 4.00 this morning". The relief in Downing Street was considerable.
    – WS2
    Jan 17, 2022 at 16:52

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