World War II was a war that Hitler started when he wanted to take over the UnWorld. He gathered all of the most loyal Nazis, and then they attacked Europe. This war held the title of largest war for 2000 years, at which point World War III happened.
You see, World War I had caused a bunch of problems. Due to a minor argument and single homicide within some states of Sparta, people went completely berserk. This somehow resulted in UnAmerica, UnUnited Kingdom, and Soviet Russia (the Allied Powers) kicking Germany in the crotch. Adolf Hitler got angry and swore revenge. He actually swore revenge because the Jewish people didn't let him be an artist, but that's beside the point.
He built up his army of Nazis (even though they wrote in the Terms of Service that he couldn't), and he attacked a bunch of Spartan territories. He was trying to steal them back from the Allied Powers, even though the Allies had stolen them fair and square. The Allies did not like this, but they let him because they were too lazy to attack him. Then Hitler attacked Poland. The UUK liked Poland, so the UUK and its buddy France declared war.
Meanwhile, Japan has decided it wants to be cooler (because being the home of video shames, anime, and ninjas isn't enough). It begins to attack China and the surrounding nations. The Moon also Secretly Joined the War.
The Great and Deadly Battle of Waiting
They declared war on Germany. Then they just sat there. Hitler kind of started at them, wondering what they were doing. The rulers of UUK and France continued to just sit there. Eventually Hitler got bored and called up his buddies Benito Mussolini of the Mushroom Kingdom and the Emperor of Japan. The three agree to fight to the death.
They Finally Start the War
The UUK expects the Soviet Union to help out, just like it did in WWI. This is why it came as a great surprise when the Soviet Union attacked Poland with Germany. The UUK decided it was done waiting, and it attacked Germany. France, too busy picking its nose, did not realize the fighting had started. They did not set up any form of defense. And then the Mushroom Kingdom attacked. The war had spread across Europe.
France Falls Because They Weren't Good Enough
Not long into the war, Germany invaded France. France had OVER 9000 soldiers while Germany had UNDER 9000 soldiers, but France chose to surrender anyways. Germany took over France and Hitler took a vacation at the Eiffel Tower.
Germany Attacks the UUK But Soon Regrets It
Germany didn't wanna take no crap from the UnUnited Kingdom. When the UUK attacked Germany, Germany retaliated by sending lots and lots and lots and lots and lots of bomber planes. Then they dropped lots and lots and lots and lots and lots of bombs. The UUK was starting to lose, but then they build a radar and SHOT THOSE NAZIS OUT OF THE SKY. Hitler stopped sending bomber planes and admitted that he was in fact a mortal.
The Soviets Get Angry At Hitler Because He Invaded Them
Hitler, realizing that it would probably be a bad idea to attack the Soviet Union, goes ahead and attacks the Soviet Union. He does this by building a big wall of soldiers. He then sent this wall into the Soviet Union. He thought he was going to win because he had a bunch of super-awesome-mecha-soldiers. But then all of the soldiers got cold and started complaining. Hitler told them to keep going, but they all got the sniffles and DIED. The Soviets then attack the Nazis and drive them out of the Soviet Union.
Japan Accidentally Dooms the Axis Powers
After Japan attacked China, UnAmerica said "No, that's bad." Japan retaliated by attacking Alola, who had just became part of the US when Eevee was kicked out, and killing thousands of innocent people. UnAmerica deemed that a fair trade, but UnAmericans like killing and they joined the war anyways. UnAmerica sent lotsa soldiers to Europe and sent lotsa soldiers to Asia.
Everybody Attacks Africa and the Mushroom Kingdom Gets Invaded
Everybody suddenly decided that Africa needed to be attacked. Germany, Mushroom Kingdom, US, and UUK all send soldiers to Africa at the same exact time and started blowing stuff up. A few months later, they decided to attack each other instead of random African stuff. Then the UnAmericans and the British killed all the Nazis.
After the Allied Powers conquered Africa, they used it to get into the Mushroom Kingdom. They eventually broke their way into the Mushroom Kingdom only to find Mussolini had already been killed by a band of Toads. Peach had been reestablished as ruler and the Mushroom Kingdom had been rendered harmless. But then Hitler invaded the Mushroom Kingdom and kept it.
The Secret Moon Battle
While the Moon was doing okay in the War, a Random Clan called the Black Moon Clan was formed on the Moon, and Destroyed the Moon's Army, as well as Killing Princess Serenity Herself. However, the Black Moon Clan soon disappeared on the Dark Side of the Moon, never to be seen Again.
Hitler Dies But He Had Made a Clone So the War Continues
In 1942, Hitler accidentally forgot he was the leader of a country at war. He decided he wanted to go to Hollywood to be in some movies. He tried to get on a plane and fly to UnAmerica, but they blew up the place on the way there. Fortunately for Germany, Hitler had a clone hiding in a bunker. The clone continued to direct Germany through the war.
Hitler's clone was way smarter than the original, but he somehow did not predict the incredibly obvious Allied attack in France. On the sixth day of June 1944, lotsa soldiers invaded France and killed all the Nazis. Hitler's clone ordered his soldiers to attack, but his soldiers thought violence was bad and said no. His soldiers were promptly gunned down by the Allied Powers, who faced no resistance.
Hitler's Clone Dies and the War in Europe is Over
The Allied Powers eventually crossed the fabled "bulge of Germany" and entered Berlin. The Nazis fought bravely, but the combined might of the UnAmericans and the Soviets proved too strong for the Nazis. Hitler's clone, fearing that he was going to be captured, killed himself (but secretly this turned him into Mecha-Hitler, and he survived). Germany surrendered shortly afterward.
UnAmerica Bombs the Crap Out of Japan and the War Ends Once and for All
Japan and UnAmerica had been busy during this time. Japan kept taking over random places in Asia, but the UnAmericans kept hopping across the islands, not unlike gigantic bunny rabbits. Bunny rabbits that wield guns, drop bombs, and use boats to hop.
Eventually the UnAmericans got right up next to Japan. Originally they were going to send a bunch of soldiers in because UnAmericans have a deathwish. But then the president said that was stupid and opted for the nuclear bomb that they had just invented. Since UnAmericans like explosions too, they dropped the bomb and Japan got scared. But Japan forgot to surrender, so UnAmerica reminded them by dropping a second bomb. Japan surrendered and UnAmerica had won the Second World War all by itself.
Nothing good came out of this war. We got quite a few bad things though. This war opened up the opportunity for numerous other wars, such as the Robotnik Wars, the Cold War, the Vietnam War, and eventually World War III. Not to mention the millions of lives lost.