Germany was down in the dumps and sour and poor after WWI. People had giant shopping carts of German Marks to buy a loaf of bread. Enter Mr. Charismatic art failure/WWI veteran Adolf Hitler. He says Jews caused all the problems and that he and the Nazi Socialist Party will fix all of it, and says Germans are superior humans and will take over the world MUAHAHAHAHA!!!!!!!!
Meanwhile, Japan stopped wearing funny hats and using old swords for warfare against themselves and caught up with the times and started using guns and tanks (albeit very puny tanks) and airplanes and stuff. They also realized they can use these new innovations to fight people other than themselves and decide that everything in the Pacific is now theirs. America glares judgingly at Japan and places an oil embargo on them. Japan is upset. FLYING TIGERS YEAH!
Hitler/Nazi controlled Germany starts annexing territory and beating up Jews and breaking their shop windows. Europeans are a bunch of baby-back bitches and are like "Hey, umm, Hitler, we'd like it if you stopped annexing territory and killing people. It sure would be swell if you just took your country and went back into being in crippling debt like before. K Thanx Bye :) --Britain" Hitler rolls his eyes and invades Poland. For some reason, Poland of all places was too damn far, so Britain and France and them declare war on Hitler/Germany. Also Hitler is teamed up with Stalin and they try to take over Finland. Some guy hiding in the snow kills a bunch of Russins. Like...a whole bunch...like, an obnoxious amount of Russins for one guy to kill...like Russians, what are you doing? Those trees and snow which could conceal a man with a rifle=death. STAHP!
Meanwhile, America is like "gee, this sure is bad. Maybe we should do something....NAHHH! Let's just make some good money and get out of this economic depression by selling weaponry and ships, and act like we're 'helping'. Yo Britain! Here's a brand new destroyer and some freight! Money please!" Germany has submarines and likes killing boats with them. This setup doesn't last long because Japan gets sick of the oil embargo and blows up Pearl Harbor. America declares war on Japan. Germany says "Fuck it, might as well," and declares war on America.
Shit's really hitting the fan now. France had a bunch of badass concrete bunkers and were like "Ho-ho! Bring it on Germany!" Germany said "Fuck that" and just drove around them. BLITZKREIG! France surrenders due to poor defensive planning. Bombs fall on London. Lots of planes fall into the English Channel. Britain is bombed and on fire and does the "come at me, bro" pose. Germany scowls after having so many planes land in the English Chanel as if to say, "I'll get you soon, my pretty!" Also Germany betrayed the USSR for some reason.
Meanwhile, America and Japan are having a bunch of naval/island battles. The invention of the aircraft carrier turns out to be an awesome investment. Apparently Japanese soldiers are fucking crazy.
Germany invades the USSR and is doing pretty well, but winter is coming.... A German fox is kicking ass in North Africa and making the allies look like fools with his expert tank driving. Italy is....Italy-ing.
America is taking more and more islands from Japan in the pacific. The tide is turning.
German fox leaves Africa to try and kill Hitler. He fails and is forced to commit suicide as execution. The Allies gain the upper hand in Africa and then invade Italy. Italy loses....badly. American and British planes launch from Britain and bomb a bunch of factories. American bombers launch from captured Pacific islands and light Japan on fire. Winter has come in Russia and the Germans are cold. The Russians climb over mountains of their own dead to push the Germans out of the motherland. Things do not look good for Germany and Japan.
Japan is still on fire and Germany's factories keep getting bombed. The time has come. D-Day. The greatest amphibious invasion ever. At Normandy. June 6, 1944. After meticulous planning and ruses, the allies launch paratroopers and beach landings at Normandy. The landing succeeds and the allies establish a foothold in France. The Russians continue pushing towards Germany via blatant disregard for human life. This is the beginning of the end for Germany.
Japanese pilots see the end coming and have gotten desperate. They go bat-shit insane and ram their own planes into American ships. America continues to push towards Japan.
Germany is pinched between the Allies and the USSR. Germany, desperate and irrationally thirsty for vengeance creates aptly named "vengeance weapons" and launches them at London. Britain shrugs that shit off, having already been bombed and on fire before and says, "Whatever Germany, you're still fucked." The Allies pinch Germany from the West and the Russians take the rubble-city of Berlin. Victory. Allies discover all the fucked up shit the Nazis did to the Jews and go "Man, that's some fucked up shit."
The author of WWII gets lazy and doesn't feel like writing a whole nother book about the invasion of Japan, so gives America a Deus-Ex-Machina-bomb. America drops it on Japan and Japan surrenders.