The Fins played the most pivotal moves in the war, able to be a strategic place which both the Soviets and Nazis wanted and even after all was said and done, they lost only a few large cities alone the Isthmus to the Russian treaty - which the Fins were not happy about, from the Winter War thru the Continuation War and the entire war the Fins fought out-numbered greatly to the Russians but they were dressed for battle and knew all the Russian tank's short-comings. A Molotov cocktail to the air intake of a tank meant one dead tank and a line of tanks who couldn't move.
The Soviets poorly arranged troops with tanks, tanks mainly on their own as if indestructible, a major blunder on Stalin's part. But when Finland allowed Nazis to build infrastructure and landing areas to refuel it kept Finland mostly in habitable shape - of course Helsinki and other great cities got slammed, no one escaped the bombs of war in Europe, not even the Fins who more than any other country played this life or death game with less loss than anyone else on the Western European Fronts.
It is amazing to see the history play out - I have a huge book called CHRONICLES OF THE 20TH CENTURY at work I'm reading, and seeing Hitler pop up as early as 1923 and 1925 - and to read his words after a short jail term as he promised his people would build in strength to seemingly impossible numbers, no one thought it could happen until the images of his 600 thousand storm-troopers gathered. From most of what I'm learning of the war, it seems Hitlers biggest blunder was NOT putting more money and development in rocket powered aircraft he thought his Panzer divisions were his main concerns throughout the war. Meanwhile, engines and planes were developed that could fly 100mph faster than the allies and with enough maneuverability to change the face of Europe forever.
Don't ever say it can't happen again - humans are followers and pack creatures. Charismatic people come all throughout history and if they have the fire-power to back up their madness, the mistakes of the past could rear their ugly heads yet again.