Sven B. L. Bergendahl volunteered for service in Finland during the Winter War.

He served from 4 March to 29 March 1940. During this time he was allocated to LeR 3 as a pilot. He also served in T-LeR 2.

Sources:
Article by Eino Ritaranta in "Suomen Ilmailuhistoriallinen Lehti" no. 1/1996 kindly provided by Carl-Fredrik Geust
Additional information kindly provided by Carl-Fredrik Geust