Schlass, ever heard of the Continuation War? In addition to the 105-day Winter War in 1939, Finland also fought the Continuation war from June -41 to September -44. After that, there was the Lapland War in 1944-1945. Do any of those fit in your timeframe?
Helsinki was among the few European capitals that were never occupied by hostile forces during WWII. That's quite a feat for a country of 3,5 million people (5 mil nowadays).