10 Wars That Were Started For Stupid Reasons
4. Everyone's Doing It (Russia Vs. Finland, 1939-1940)
In 1939, as the Second World War unfolded around the globe, Russia invaded Finland. The details of the conflict, with Russia feeding men into a frozen wilderness full of Finns who turned out to be really good shots, are well-recorded. What is absent is a reason for it all to happen.
Russia seems to have invaded Finland because that's the sort of thing everyone was doing. Germany and Russia had just divided Poland up between themselves so Russia was all invasion-happy and Finland was right there, just existing like a big frozen cake waiting to be devoured. The rest of the world was equally perplexed by the invasion and kicked Russia out of the League of Nations.
Fun bonus fact - the Russian politician Vyacheslav Molotov claimed the bombs his air force was dropping on Helsinki were humanitarian aid packages. The Finns called the bombs 'Molotov's bread baskets'. They coined another blackly humorous name for the improvised firebombs they used against Russian tanks: the Molotov cocktail.