Because they are considered as brothers. Since both of the countries are slavik, they help each other. They both have the same religion and aspects in life. When one goes down, the other one has it's back. I guess you can say just like America and England.
Treaties that Russia had with Serbia
When Russia found out that Austria-Hungary was declaring war on Serbia, they came into alliance with Serbia for several reasons.
The question doesn't specify, but I assume you're referring to World War One. The war began between Serbia and Austria-Hungary. Russia was an ally to Serbia, thus they jumped in to support their ally.
some guy from austria-hungary assassinated archbishop Ferdinand of Serbia. Serbia were allies of Russia and then Russia declared war on austria-hungary
At the begining of the war Serbia was allied with Montenegro, Russia and Greece. Greece stayed neutral in war, while Montenegro and Russia helped Serbia to fight with Austria-Hungary. When Serbo-Austrian war became World war Serbia alongside Russia and MOntenegro was part of Entante (Allies).
Russia was a country that had a lot of Slavic people. Serbia was also a Slavic nation.
It was a World War because a man killed the archduke of Austria-Hungary in Sebia. Austria-Hungary declared war on Serbia. Serbia had an alliance with Russia and then Russia joined the war. Russia was in the Triple Entante and pulled Britain and France into the war. Austria-Hungary had alliances with Germany and the Ottoman Empire. They also joined the war. That is why World War I was a world war.
France and Great Britain allied with Serbian during World War 1. Serbia was the first country to be attacked in World War 1.
It was a World War because a man killed the archduke of Austria-Hungary in Sebia. Austria-Hungary declared war on Serbia. Serbia had an alliance with Russia and then Russia joined the war. Russia was in the Triple Entante and pulled Britain and France into the war. Austria-Hungary had alliances with Germany and the Ottoman Empire. They also joined the war. That is why World War I was a world war.Read more: Why_was_world_war_a_world_war
It was a World War because a man killed the archduke of Austria-Hungary in Sebia. Austria-Hungary declared war on Serbia. Serbia had an alliance with Russia and then Russia joined the war. Russia was in the Triple Entante and pulled Britain and France into the war. Austria-Hungary had alliances with Germany and the Ottoman Empire. They also joined the war. That is why World War I was a world war.Read more: Why_was_world_war_a_world_war
They went to war with Russia since Russia wanted to help Serbia since they were allies.
They went to war with Russia since Russia wanted to help Serbia since they were allies.
Russia declaring war on Germany to protect its ally Serbia