The Viena expedition was a military expedition in March 1918 by Finnish volunteer forces to annex White Karelia from Soviet Russia. It was one of the many "kinship wars" (Heimosodat) fought near the newly independent Finland during the Russian Civil War. Russian East Karelia was never part of the Swedish Empire or the Grand Duchy of Finland. and it was at the time mostly inhabited by Karelians. However, many advocates of a Greater Finland considered these Karelians a "kindred" Finnish nation and supported the annexation of Russian East Karelia to Finland.

The Finnish term Heimosodat refers to a series of armed conflicts and private military expeditions in 1918–1922 into areas of the former Russian Empire that bordered on Finland and were inhabited in large part by other Finnic peoples. The term has been translated into English as "Kindred Nations Wars", "Wars for kindred peoples", "Kinfolk wars", or "Kinship Wars," specifically referring to Finnic kinship. Finnish volunteers took part in these conflicts, either to assert Finnish control over areas inhabited by related Finnic peoples, or to help them gain independence from Soviet Russia. Many of the volunteers were inspired by the idea of "Greater Finland". Some of the conflicts were incursions from Finland, and some were local uprisings in which volunteers wanted either to help people fight for independence or to annex areas to Finland. According to Aapo Roselius, about 10,000 volunteers from Finland took part in the armed conflicts mentioned below.Estonian War of Independence (1918–1920) Pohjan Pojat and 1st Finnish Volunteer Corps helped Estonian troops. Viena expedition (1918) Murmansk Legion Aunus expedition (1919) Petsamo expeditions Revolt of the Ingrian Finns (1918–1920) East Karelian Uprising (1921–1922)