Russian Empire
The Russian Empire, also known as Imperial Russia or simply Russia, was an empire that existed across Eurasia and North America from 1721, following the end of the Great Northern War, until the Republic was proclaimed by the Provisional Government that took power after the February Revolution of 1917.
Russian entry into World War I
On 30 July, Russia declared general mobilisation in support of Serbia; on 1 August, Germany declared war on Russia, followed by Austria-Hungary on 6th. Russia and the Entente declared war on the Ottoman Empire in November 1914, after Ottoman warships bombarded the Black Sea port of Odessa in late October. Unlike its Allies, Russia's Empire was one contiguous landmass but it also considered itself the defender of its fellow Slavs in countries like Serbia.