I would've posted this last year but I found this recently. (Also please don't start talking about WW2 politics, this is just a anniversary topic)
This song is about the Battle of Wizna, where Poland fought 3 days against ~40,000 Germans. Poland only had ~720 troops, the ratio between the two is 40:1. Weirdly enough the Swedish band Sabaton made this song, and not some Polish band. ^^