The Eastern Front of World War I (Russian: Восточный фронт, sometimes called the "Second Fatherland War" or "Second Patriotic War" (Russian: Вторая Отечественная война) in Russian sources) was a theatre of operations that encompassed at its greatest extent the entire frontier between the Russian Empire and Romania on one side and the Austro-Hungarian Empire, Bulgaria, the Ottoman Empire and the German Empire on the other. It stretched from the Baltic Sea in the north to the Black Sea in the south, included most of Eastern Europe and stretched deep into Central Europe as well. The term contrasts with "Western Front", which was being fought in Belgium and France.