France and England enter World War 2 following Germany's invasion of Poland. But with the exception of its navy England is rather uncertain how to prepare. After a failed operation in Norway lead by Churchill, Chamberlain is, ironically, replaced as Prime Minister by Churchill.
Following the defeat and retreat at Dunkirk, Britain desperately works to rearm and prepare their defenses. But Germany was not well prepared to press their offensive and invade. After losing the Battle of Britain Germany begins bombing British cities. The British launch an offensive in North Africa hoping to distract the Germans attention from the British Isles.
Following the conquest of France Hitler, almost casually by blitzkrieg standards, turn his eyes toward Russia. But Stalin is equally lackadaisical in preparing defenses against Germany. The German invasion rapidly reaches the gates of Moscow where it is stopped cold by the onset of winter then crushed by the Russian counterattack.
Following Japan's conquest of eastern Asia the Allies finally respond with sanctions. They prove so threatening to Japan that it prepares to conquer Southeast Asia to secure the resources it needs. But first the threat from the British and American Pacific fleets must be eliminated.
Although those in the know figured it was just a matter of time, the United States only reluctantly participated in World War 2. But it was not a foregone conclusion that the United States would side against both Germany and Japan. Japan's attack on Pearl Harbor precipitated a quick decision. But in Germany's case a long series of mutual provocations, some intended, some not, gradually turned the United States against Germany.
In 1940 Mussolini deploys a massive army to invade British held Egypt, to capture the Suez Canal and most of all to establish an Italian empire to rival Germany's. So begins a multi-year campaign over a meaningless stretch of desert involving forces from a dozen nations and characterized by persistent attackers, stubborn defenders and ultimately controlled by supply line challenges.