Germany executes its invasions of Yugoslavia and Greece, and the Axis encourages an anti-British coup in Iraq.
As Germany made preparations to assist its ally Italy in the war against Greece, a coup in Yugoslavia prompted Adolf Hitler to order the invasion of that country as well.
In summer of 1940, even as the Battle of Britain was just getting started, Adolf Hitler was already laying plans for war with the Soviet Union.
After the fall of Poland, British Intelligence's codebreaking operation at Bletchley Park became the center of efforts to decrypt messages from the Germans' supposedly unbreakable Enigma machine.
The British had been hugely successful at breaking German codes in the First World War. The Germans were determined not to let that happen again. This time they had Enigma, a code machine that produced messages that could not be decrypted. Or so the Germans believed.
The navy Germany had at the outbreak of the Second World War was only a small fraction of what the Allies had arrayed against it. But the Fall of France and the entry of Italy into the war changed things dramatically and created opportunities at sea that Germany had never had in the last war.
In 1940, the British government was in the frustrating position of funding research on a number of promising projects that would be valuable to the war effort, but with the Battle of Britain in full swing, British factories had to turn out fighter planes as fast as they could. There was no room for development of experimental new technologies, so the British turned to the United States
Italy's invasion of Greece was disastrous. With the British also advancing in North Africa, and a surprise air attack disabling three Italian battleships, it was no longer possible to pretend that Italy was a equal of Germany.
Benito Mussolini wanted to prove that Italy was an equal partner with Germany in the Axis alliance, so he began a war with Greece.
Germany found that it could not defeat the British on their home island; the UK was unable to fight the Germans in Europe. So what next?