A couple depressing "end of days" films:
https://en.wikipedia.org/wiki/Salvador_(film) Oliver stone. James Woods. Based on true events
https://en.wikipedia.org/wiki/Children_of_man Clive Owen has to save last fertile girl on earth.
A couple realistic foreign war films:
https://en.wikipedia.org/wiki/The_9th_Company Russian troops in Astan
https://en.wikipedia.org/wiki/City_of_Life_and_Death Battle of Nanjing