Tangential, but a fun fact.
"Czapka" in polish just means "a hat". And that's any hat - winter, knitted, baseball cap, etc. (Apart for brimmed hats, those are called "kapelusz").
The hat that Polish soldiers wore around the Napoleonic era is called "Rogatywka" in Polish, sometimes translated as a "four-cornered hat" into English. Googling for the name is not helpful though, because the name is the same for any form of "four-cornered hat" that's been in use in Polish military and police services till today. So if you want to google for it, enter "Rogatywka wojny napoleonskie" ("four-cornered hat Napoleoinc Wars).