Törni is famous because of his courage in the Continuation War (1941–44) between the Soviet Union and Finland. In 1943 he was the leader of "Detachment Törni". His infantry unit went behind enemy lines to attack the Russians. One of Törni's men was future President of Finland, Mauno Koivisto. The two served together during the Battle of Ilomantsi. This was the last Finnish-Soviet battle of the Continuation War.