Consider the following scenario: Authoritarian Russia invades a small, democratic neighbor. Western democracies express support for the targeted nation but decline to send troops. The Russian army gains ground. Cities are bombed. The smaller country is outnumbered and outmatched. Few expect the war to last long.

But the invasion prompts a fierce resistance. The defenders know and use their terrain, and they deploy inventive tactics to exploit weaknesses in the Russian army. Thousands of Russian soldiers are killed, and the war grinds to a stalemate.

Ukraine in 2022? Yes — and also Finland in 1939.

More than 82 years ago, Joseph Stalin invaded Finland, aiming to capture territory and replace Finland’s democratic government with a puppet Communist regime. Then, as now, the war followed an unsuccessful Russian campaign of threats and coercion. And then, as now, the war did not go as planned for the invaders. The outgunned Finnish army mounted a determined defense of their nation, surprising even themselves — and embarrassing the Red Army.

The Winter War of 1939-1940 is remembered today mainly as a lesson in territorial defense tactics. But thinking about that war reveals important insights into the origins of the war in Ukraine — and how it might end.