This was called the "Anschluss", thus pretending that Austria voluntarily joined Germany.
Austria-Hungary declared war on serbia and Germany joined because it was allied with austria.
Joined the Allies.
Bulgaria
Germany joined Austria-Hungary and Italy to create the triple alliance.
Italy
Ottoman Empire
Austria-Hungary. They were subsequently joined by the Ottoman Empire and (in 1915) Bulgaria.
Germany, Austria, and Hungary on the Central powers, and Great Britain, France, Russia. those were the Allies. These two are stated at the beginning of the war. others had joined by the end of it.Triple Entente: France, Russia (and Serbia Pan-Slavism), Great Britain. Italy joined in 1915 From the Triple Alliance. and the United States in 1917.Triple Alliance: Germany, Austria-Hungary, and Italy. The Ottoman Empire joined in 1915.
In the 1879, the Dual alliance (Germany and Austria) was made and then Italy joined in 1882 which made the Triple alliance.
Serbia and Austria got into a fight. Russia sided with Serbia as Serbia's "big brother". France and Russia were friends so France joined in. Germany and Austria were friends so Germany sided with Austria. Then Germany invaded Belgium (who tried to stay impartial) to attack France. Britain got involved as there was a contract/agreement between Belgium and Britain from a 100ish years ago saying that Britain will help protect Belgium in a war (Britain felt left out) then America joined later. so in odder of who joined first Serbia Austria Russia Germany France Belgium Britain America
The emperor of Austria was shot in a car. Then russia declared war on them and Germany helped their allied Austria and then France was attacked by Germany too (Why I dont know) And then GB attacked Germany. Then we joined in and beat the crap out of them!