Although in the early stages of World War I, Germany used rigid airships to attack England from the air and the Allies launched some counterattacks on Germany, it was not until World War II that the threat of aerial attack on cities became sufficiently great to call for organized civil defence planning. While a few special air-raid shelters were built in the UK and in Hawaii, civil defence tactics during the interwar years consisted principally of utilizing improvised shelters such as basements and subways. Germany also built special bunkers for a small fraction of its population, and these proved to be very effective in saving lives. Other civil defence tactics (in Great Britain and along the coasts of the USA) consisted of blackouts to reduce the night glow from city lights that could have served as guides to enemy pilots. The British government provided gas masks for its people, and practically all the countries involved in the war trained citizens in the elements of fire fighting, rescue and medical first aid.
The major, perhaps critical, difference between the civil defence situation in World War II and that which has confronted the world since 1950 is that while the relatively small weapons of World War II afforded some 'learning time' - people could learn by experience that shelters were safer than ordinary buildings and civil defence volunteers could be recruited and trained after the war had begun - no learning time is allowed by nuclear weapons that can destroy whole metropolitan areas at one blow. There is no opportunity to learn from repeated attacks because the first attack in all probability, will accomplish its mission.