The Battle of Britain is a vast subject. It was fought for almost four months, witnessed by millions, and was documented widely and in detail. Let's focus here on one topic, the key causes for the German defeat in the Battle of Britain. These causes were bad senior leadership, and bad intelligence analysis, and they cursed the Luftwaffe (German Air Force), and the German war effort, for the rest of World War 2.
The German Grand Strategy
Adolf Hitler originally intended to conquer the world one enemy at a time. He also trusted that continued European appeasement, and American isolationism, would allow him that. He wanted to conquer Eastern Europe first (Poland, then Russia), and then to exploit its vast resources to convert Germany, over one decade, from a European power to a global super-power, and then to turn West, conquer Western Europe, then defeat Great Britain, and finally fight against the United States of America for global domination.
The first setback for Hitler's grand strategy was when Great Britain and France surprised him by declaring war in response to his invasion of Poland. Hitler's response was to attack in the West, temporarily he hoped, in order to settle that unexpected problem, and then be able to turn back East. His 1st step was to secure his northern flank, Scandinavia, which was a vital source for war materials. His 2nd step was to defeat and conquer France. And the result of that, he believed (and wrote to his generals), was that Great Britain, remaining alone at war against Germany, and at a "militarily hopeless situation", would prefer to negotiate an end to the war.
The second setback for Hitler was when Great Britain, then led by a new prime minister, Winston Churchill, refused to negotiate an end to the war. This forced Hitler to a 3rd step in his war in Western Europe, making preparations for an invasion of Britain, in hope that either that would convince the British to negotiate an end to the war, or, if necessary, invade...