how bad it could have gotten

The British in one sense were lucky when Hitler turned and repeated history by invading Russia which subsequently led to his downfall and the destruction of the Third Reich, however for a time the United Kingdom did stand up against the mighty Reich after watching its powerful ally France being crushed in a matter of weeks, the famous Battle of Britain know for its large scale air engagements saw the RAF outnumbered but far from being defeated, what saved Britain to be able to actually engage Hitlers Germany was Hitler turning to engage the Soviet Union, in a war that would kill millions.



But the British were lucky not to have to endure a direct full on total war with Nazi Germany in 1941, the Battle of Britain we know had seen Britain's air and naval forces stretched to the limit whilst the ground forces were readied to resist an invasion, but the British had already taken on a permanent war economy, stretched to the limits the British economy would have exhausted basic needs for its citizens, that followed by round the clock bombings of British cities after the eventual defeat of the RAF would have made surrender and eventual defeat inevitable for Britain.



But right off the bat Britain could have probably as Churchill put it "postpone martyrdom" against the might of the Nazi military machine for a good two years before the eventual breaking up and disillusion of Britain's armed forces (if America up to this point didn't join the war directly declaring war on a less preoccupied Germany), with the Royal Air Force and Royal Navy defeated if unable to mount a successful landing the Germans could have easily by this point made every aspect of life hell for British citizens, for instance as in the real war in 1945 battering London and other British cities with a new weapon, the V2 ballistic missile.



Any landing by the Germans would have been a bloodbath, but that being said having total air superiority with only barely sufficient anti aircraft guns to face they could have easily laid waste to dug in British forces in a matter of days such as they did with the Maginot Line in France in 1940, a large scale invasion of Britain would have surely resulted in large scale fighting from an already war weary people.


Home Guard light reconnaissance cars in Scotland circa 1941

As in the Allied landing in Normandy it would require huge logistics but focusing its war economy on it the Germans would have surely come up with such logistics necessary to execute such a landing.

After the general defeat and post war break up and confusion of the Home Guard the following wide scale resistance would have had irritating effects on the occupying force but it would have been hell for the British that would have had to endure it!

But one thing was for sure, Churchill as promised would have most likely led a rag tag resistance force up north and fought against the Nazis no matter what!



That being said if it wasn't for one impatient decision by Hitler to turn his military might against the Russians (which were halted by the winter of all things) and thus repeating once again the European desire to conquer Russia he saved Britain from certain annihilation.