From 1914 to 1918 Europe celebrated the culmination of the most impressive societal advancements in the history of the world by trying to screw it all up meaninglessly.
World War One is the forgotten war. Mostly because those who lived through it are now so old they can't remember anything about it. World War One is not as cool as World War Two because the villians in it weren't particularily impressive, kind of like Star Trek Episodes featuring the Romulans as villians instead of the Klingons... we just can't be bothered to care much.
"Just Not As Interesting as Klingons or Nazis"
Austria wanted to put the smack down on Serbia for this, but feared Russia would help Serbia since they're both Slavs, whatever that means (we think it's something sexual and kinky). So Austria does what it always does and calls in big brother Germany to help bail its ass out. Problem is that Russia signed a treaty with France declaring they'd got each other's back (yeah, as if nobody wanted to mess with France). England being all English had singed a secret treaty of the same nature with France. Apparently England didn't understand if the whole "strength in numbers" thing was going to work it required EVERYONE TO KNOW WHICH SIDE YOU'RE ON! Neewbs.
Not the Archduke, But Still Should Be Shot.
So Germany decides to march through Belgium to avoid France's defenses and presumably to pick up some awesome waffles to entice easy French women (yes, that's redundant). England gets pissed that Germany would violate neutral Belgium and comes into the war publicly. This would have worked out better if England had an actual army. Instead a rag-tag group of volunteers decide to sign up and go off to die horribly after being mismatched against Germany's professional killing machine. Everyone dug trenches because they weren't allowed to run backwards and they couldn't overrun the enemy so they just dug down. Then they tried to use machine guns to kill anyone who poked their head out of the trenches like they were playing a big ass game of whack-a-mole.
Fortunately, the trenches convert to graves rather easily.
After some time Germany gets the Ottoman Empire (Turkey with a cooler name) to go bother Russia. Meanwhile it took years before America finally got into the war when President Wilson would no longer have to worry about elections and when he realizes America's entire economy was greatly linked to England's. Wilson had to ask banker J.P. Morgan to finance the war proving that Banks do in fact run everything in America. They can also ruin everything in America as we have recently seen.
A lot of fighting goes down (most of it before America gets in the war) and the Allies (which we Americans remember as the USA, England, USA, France, USA, Italy, USA, and briefly Russia) win the war.
You're Welcome, Earth.
All of J.R.R. Tolkien's writing buddies bite the bullet. He gets hurt, goes home and steals all he can remember from his dead pals and becomes a literary giant. Somehow Tolkien goes on to become the only WWI vet writer who has good triumph evil in his books, which tells us how little he liked his friends.
The most brillian young chemist in the world was an English chap who signed up to go to war. The English had no way of determining who would be more usuful in science labs then the trenches so he dies. No, we don't know his name either because he was killed before he became the Einstein of Chemistry.
Hitler's left nut supposedly bought the big one in the war too. This is probably made up, but it's not like anyone's going to sue us to defend his good honor.
"Way to Drop The Ball, Adolf!"
Thanks to America's big Calvary act the Allies win the war. At the post-war huddle the Central Powers are forced to take all the blame and pay back a mountain of gold deblumes. Even President Wilson thought the British and French were being greedy bastards about this, but they told him to go to hell. Now that the war was over the French and British thought they'd never need America's help again.
Unfortunately the producers of World War One totally left the storyline open for a sequel.