1) Period 2) Period of conflict 3) Period of major fighting 4) Period of strife 5) Period of time 6) The early 1940s 7) Time period 8) When goods may be rationed 9) When M*A*S*H was set 10) When there may be censorship 11) When to support the troops 
[n] - a period of time during which there is armed conflict
noun a period of time during which there is armed conflict