Why did russia enter world war 1?
There wasn’t an explicit alliance between Serbia and Russia – however, there was a certain ‘affinity’ between the countries (religious, linguistic, cultural). 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).
