Slaughterhouse Five if the book doesn't need to have even a tenuous hold on reality, or Mother Night, also by Vonnegut.
There are several Russian novels about World War II that are certainly worth it in terms of being well-written, like Vassily Grossman's За Правое Дело (For the Right Cause) and its critically acclaimed successor Жизнь и Судьба (Life and Fate). Konstantin Simonov also wrote a trilogy called Живые и Мертвые (The Living and the Dead), but it may be a bit too much in the realm of "socialist realism". Boris Vasilyev wrote a lot of very good shorter stories about the war as well. I couldn't tell you about translations, though - they probably exist but I can't vouch for any quality.
There are also a lot of novels that became popular movies but I'm not familiar with the novels that inspired the movies at all, like Bridge Over the River Kwai or The Thin Red Line.
ἡ δὲ κἀκ τριῶν τρυπημάτων ἐργαζομένη ἐνεκάλει τῇ φύσει, δυσφορουμένη, ὅτι δὴ μὴ καὶ τοὺς τιτθοὺς αὐτῇ εὐρύτερον ἢ νῦν εἰσι τρυπώη, ὅπως καὶ ἄλλην ἐνταῦθα μίξιν ἐπιτεχνᾶσθαι δυνατὴ εἴη. – Procopius
Ummaka qinnassa nīk!
*MySmiley*
