This book is George Orwell's first-hand account of the Spanish Civil War just before World War 2. It is an absolute
must read. You'll understand why when you start getting through it. It will help you understand Animal Farm and 1984 better.
If I recall correctly, there were times when he was holed up with a unit in a city building anxious to see what flag was raised on top the building across the street in the morning. And war stories you
have to read if you're a history buff. It's the same story I read about socialism/communism over and over again. They turn on their own. And then the rats come...
https://en.wikipedia.org/wiki/Homage_to_Catalonia