In 1918, he took part in the Finnish Civil War as a lieutenant of the White side. Among many of his known accomplishments, General Raappana was chosen to command the Finnish detachment - nicknamed "Group Raappana" ("Ryhmä Raappana" in Finnish) - that was to stop the enemy in the very final Finnish-Soviet battle during World War II.
In 1918, he fought on the White side of the Finnish Civil War. Among his notable achievements was leading a Finnish detachment known as "Group Raappana" ("Ryhmä Raappana" in Finnish) that aimed to halt the enemy during the final battle between Finland and the Soviet Union during World War II.