When Russia found out that Austria-Hungary was declaring war on Serbia, they came into alliance with Serbia for several reasons.
Serbia partially accepted the ultimatum from Austria-Hungary but rejected some of the demands. This led to Austria-Hungary declaring war on Serbia, which ultimately sparked the beginning of World War I.
The assasination of the Austrian heir to the throne led to Austria invading Serbia and Russia declaring war on Austria. Then Germany helped Austria while Britain and France declared war on Germany.
They went to war with Russia since Russia wanted to help Serbia since they were allies.
Germany, Austria/Hungary, and Italy by the Triple Alliance!!
Answer this question… Russia had an alliance with Serbia, and Germany had an alliance with Austria-Hungary.
Austria.
They went to war with Russia since Russia wanted to help Serbia since they were allies.
Technically, Serbia. However WWI is widely referred to by Historians as 'The War Nobody Won'. Austria declaring war on Serbia, the Serbs’ allies Russia declaring war on Austria, the Austrians’ allies Germany declaring war on Russia and the Russian’s allies France and Britain declaring war on Germany. America eventually entered on the side of Serbia et al due to a few incidents with German U-boats and Germany surrendered. If you work backwards operating under the system of official declarations via the various alliances the winner is Serbia (whose country was mostly pounded into gravel in the process) and their allies: Russia, France, and Great Britain.
Russia
Russia declaring war on Germany to protect its ally Serbia.
They turned to Germany when Russia declared war on the Austro-Hungarian Empire for declaring war on Serbia, when Serbian nationalist killed the Arch Duke Fernand and his wife while they were in Serbia.