Germany was only formed in 1871.
It is a region in the centre of Europe that was historically the playground of the European powers. But here comes Prussia with their millitary might who conquered all other German states and unite them into the first German empire. Germany starts industrialising heavily and despite being a latecomer to the game, they're on their way to world domination.
So the old powers of Europe, Britain France & Russia start to feel insecure in the power and want to destroy this new and rising Germany before it becomes THE superpower of Europe. The Russians predicted that by around 1920, Germany would've gotten so industrialised and developed it would be impossible to defeat them. So they take the opportunity to go to war with Germany. On the central powers side you had the failing powers of Europe, Austrian & Ottomans who allied with Germany.
People say this was fate but the Ottomans weren't destined to join German's side in the war. You had some pashas like Talat pasha who wanted to join the west and some like Enver Pasha who was a strong supporter of Germany after visiting there and falling in love with their militarism ethno nationalism which he wanted to bring to the Ottoman empire with his new brand of Turkish militarism. Meanwhile the Ottoman Sultan/Caliph Mehmed V (1909-1918) wanted to stay neutral but he was a puppet of the 3 pashas(a millitary junta that too over the Ottoman empire after 1908).
Eventually all this yapping was ended when Enver pasha got a few ships and flew the Ottoman flag on it then attacked Russian ships in the back sea causing Russia to declare war on the Ottamans and forcing the Caliphate to enter ww1.
The Austrian-Hungary empire was just a mess. Even young Adolf Hitler illegally went into Germany and fought in that army because of how ass and doomed Austria was. Literally a bunch of ethnic German(Austrians) Hungarians, Slavs and a few Albanians. Cramped into a single state who all hated each other and did Al shabab style bombings on each other.
