When the Soviet Union invaded Finland in 1939, Russian leadership thought the country would be easily conquered.
After all, the Soviets had one of the world's largest militaries, while Finland had one of the smallest. The Finns were monumentally outmanned and outgunned.
Yet the Finns put up a gritty, prolonged, improbable resistance that surprised and inspired the entire free world.
The secret to the Finns' stand was a quality they call sisu.
There isn’t a single word in English with a literal parallel to Sisu, and even in Finland it stands in for a constellation of traits, which includes stoic determination, hardihood, bravery, willpower, tenacity, guts, and resilience. Grit.
