One of my favorites is
Mila 18 by Leon Uris. It tells the story of the German occupation of Poland, and Warsaw during WW2. A large part of the story concerns the Jewish uprising and defense of the Warsaw ghetto.
Another favotite is
Red Storm Rising by Tom Clancy, which deals with a possible WW3 scenario between NATO and the USSR. It's more modern, going into a lot of detail of battle strategies.
I'm found both of these excellent reads.