Farewell of Slavianka is a Russian patriotic march originally written in 1912 by Vasily Agapkin. It gained popularity in the First World War and was even the unofficial anthem of Kolchak's White Army.
During the Battle of Moscow, the song was played during the parade on Red Square. It gained in popularity due to the Soviet film «The Cranes are Flying» in 1957 with new lyrics added, marking the march that most of us hear today.