Why did Russia enter the 1st World War?

Answer 1

Russia entered the war after Austria declared war against Serbia, because Russia had made itself the guardian of all Slavic and/or Eastern Orthodox peoples, particuraly the South-Slavs in the Balkans who had for centuries been under Muslim-Ottoman domination.

Answer 2

Austria had taken advantage of Russia's problems in the wake of defeat in the Russo-Japanese War to annex Bosnia-Herczegovina in 1908. At that point Russia was unable to act, however, they did determine not to allow Austria to make any further such gains in the Balkans. When Austria issued the ultimatum to Serbia in 1914, and threatened to attack, Russia warned Austria and started a partial mobilization themselves. This is were the system of alliances kicked in, because Germany mobilized in reaction and ultimately declared war on both Russia and France (France had an alliance with Russia).

Answer 3

One is tempted to respond "read a history book", but the short answer is: because Germany declared war against them. This wasn't entirely without provocation, mind you, which is where the history book would come in handy.

Essentially: Germany supported Austria-Hungary, while Russia was friendly with and supported Serbia. When the Heir Apparent of Austria-Hungary was assassinated by Serbian militants, Austria-Hungary and Germany began preparing for war with Serbia, and Russia began mobilizing its forces to support Serbia. The Germans objected to this mobilization, and eventually declared war on Russia.

There's a whole lot of stuff left out in there, but really, it all boils down to a complex web of alliances and preferences with, ultimately, the Triple Alliance (Germany, Austria-Hungary, Italy) on one side, and the Triple Entente (Russia, France, Britain) on the other, and a bunch of minor players like Bulgaria and Serbia on the sidelines egging them both on.

Answer 4

Russia declared war on Austria-Hungary to support their ally Serbia. This forced Germany to declare war on Russia to support their ally Austria-Hungary.

Answer 5

Russia is a Slavic country, and it entered WW1 to come to the aid of fellow-Slavs, the Serbs, who were being attacked by Germany and Austria-Hungary.