High Quality Content by WIKIPEDIA articles! Civil defense (civil defence), (see spelling differences) or civil protection is an effort to protect the citizens of a state (generally non-combatants) from military attack. It uses the principles of emergency operations: prevention, mitigation, preparation, response, or emergency evacuation, and recovery. Programmes of this sort were initially discussed at least as early as the 1920s and were implemented in many countries, but only became widespread in the USA after the threat of nuclear weapons was realised.