Hey Russia and Britain do you wanna have an alliance and declare war against Austria-Hungary?
I guess, yeah
Once the war was in full force in Europe, two major alliances were formed; the Triple Alliance and the Triple Entente. The Triple Alliance contained Germany, Austria-Hungary, and Italy. The Triple Entente contained Russia, France, and Great Britain
Austria-Hungary invades Russia.
They are invading us
We gotta fight back
USA joining war
On April 2, 1917, the United States joined World War I when they declared war on Germany. They did this because of the Zimmerman Telegram and because of German U-Boats sinking civilian ships containing US citizens.
Treaty of Versailles
By November 1918, the Allied Powers were triumphant in the war as all Central Powers had surrendered, with Germany being the last to do so. Germany was then forced to sign the Treaty of Versailles, which stated that they had to give up much territory, reduce their army and navy, and pay massive amounts of reparations.