Franz Ferdinand got assassinated by a Serb meanwhile Serbia is all cool with what's happening but Austria will not talk to them nor will they negotiate with whatever plan they have. Leave it to Russia to move to back it's Slavs. Meanwhile with all of this going on Germany's like "hey join me" and AH is like "alright cool" Russia doesn't like that so it declares war. Meanwhile Russia and France have joined alliances and they make this plan called the Schlieffen Plan: go west,attack and fight France then yay we're done! But in order to get there they'll have to go and cross Belgium ,England notices and is like "hey I wanna fight along side you guys" so England is now an ally to France and Belgium. Meanwhile Europe hasn't been noticed yet so their like "I'm mad so I'm gonna fight to get your attention" so Europe fights in WW 1,the war starts in the summer of 1914, but that causes some problems. So that calls for an Alliance system(s)-Colonies,militarism and nationalism( yay!!!!!) so now the wars begun.
The allies stop the German allies form swarming at the battle of the Marne meanwhile while they are there they get caught in the crossfire thus begins them digging trenches to protect themselves from the enemy across from them but they can't move since in between them and the enemy is what you call "no mans land" if you were to crawl out of the trench and onto the land you'd get fired and shot at. Killing you instantly or you would be bleeding out with no one to come to your rescue since if someone did they'd get shot at to (or blown up since land mines are a thing).
(Let's not talk about Verdun long story short we of course won since we are THAT awesome)
After that is won we STILL have another war to fight: the battle of the Somme. That leads to millions upon millions of soldiers dead with just a few miles that we won, after that we think the wars are over with we can be at peace but NO SINCE THATS NOT HOW THIS WORKS. But on the bright side we have new weapons!!! Yay!!!! We will be fighting in style! Just to name a few: we have subs,tanks,zeppelins oh and planes!!! How cool is that?oh and I almost forgot we have the most deadliest and the most scariest weapon of all!!!: gas poison!!!
Where's the Americans after all this time? Oh their neutral until Lusitania annnd Zimmermann's little note to Mexico. The "yanks " so that they are called are arriving to high time they showed up. The Russians notice and are like "uh hey Czar can you um maybe escape? You know from the war and their like uh yeah let's get out of here" and so they hightail it out of the war. Oh and the Germans are back to this time with all their might they brought a treaty with them! It's called Treaty of Brest-Litovsk. But unfortunately they fall again at the Marne. Meanwhile the Americans say bye bye to Wilhelm and they sign the armistice. Thank goodness the war is FINALLY over! they get closure in Paris, a new Treaty is signed and it's called: The Treaty of Versailles. A League of Nations is born and the reparations of the allies occurs. With that created there are no more wars since that treaty is an agreement to end all wars. That war was a war to end all wars. We did it! We won!!!
