"It is only a small exaggeration to say that the Spitfire was the plane that saved the free world." There are many other reasons why Britain was never invaded

"It is only a small exaggeration to say that the Spitfire was the plane that saved the free world." There are many other reasons why Britain was never invaded in 1940: the Dunkirk evacuation saving the trained part of the army, the extensive early warning system, including radars, the preliminary work on the Enigma machine brought over by escaped Poles etc. Chief among them, I would argue, was the fact that Hitler didn't really want to fight the British after France fell, and didn't expect he would have to. The lack of investment in submarines and strategic bombers, the half-hearted and late starting planning for Sea Lion, the minimal commitment to the Mediterranean front (North Africa, Malta, Gibraltar) etc. only make sense in this light. The fact that, with proper planning and resources allocated, the German military was more than capable of taking on the British in an across-the-water operation was proven earlier in the same year by the successful operation in Norway, and next year by the capture of Crete.