Children practice the “Duck and Cover” drill, to protect themselves against the effects of a nuclear explosion, 1950s

“DUCK AND COVER KIDS! BUT THIS IS MOSTLY A FUTILE EXERCISE BECAUSE IF THE BLAST DOESN’T KILL YOU, THE HORROR OF SURVIVING WILL!”
Duck and Cover is a method of personal protection against the effects of a nuclear explosion, which the United States government taught to generations of United States school children from the early 1950s until the end of the Cold War in the late 1980s. It was intended to protect them in the event of both an unexpected nuclear attack, which, they were told, might come at any time without warning and in the event sufficient warning is given.
Under the conditions of a surprise attack, immediately after they saw a flash they had to stop what they were doing and get on the ground under some cover—such as a table, or at least next to a wall—and assume a prone like position, lying face-down and covering their exposed skin and back of their heads with their clothes, or if no excess clothes such as a coat was available, to cover the back of their heads with their hands. Similar instructions were given in 1964 in the United Kingdom by Civil Defence Information Bulletin No. 5. and, in the 1980s, by the Protect and Survive series. Under the conditions where sufficient warning is given, they were told to find the nearest Civil Defense shelter, or if one could not be found, any well built building to stay and shelter in. From Wikipedia
Ack-Ack fire during a German air raid on Algiers; 1943.

Those are the light trails that result from long-exposure photography of gunfire. Ack-ack is shorthand for anti-aircraft.
A charred body of a woman in the air-raid shelter – Dresden, February 1945.
This bombing was so complete that most people died not from the bombs but from suffocation as the city-wide fire used up all the oxygen from the air.
“…one of the air raid precautions the city had taken was to remove the thick cellar walls between rows of buildings, and replace them with thin partitions that could be knocked through in an emergency. The idea was that, as one building collapsed or filled with smoke, those using the basement as a shelter could knock the walls down and run into adjoining buildings. With the city on fire everywhere, those fleeing from one burning cellar simply ran into another, with the result that thousands of bodies were found piled up in houses at the end of city blocks…” (Source)
People so often forget Dresden when they discuss the horrors of WWII. I guess with the horror of the atomic bomb and the Holocaust the simple firebombing of a town is somewhat less horrific to discuss but the devastation caused there was nearly unimaginable.
“It is not possible to describe! Explosion after explosion. It was beyond belief, worse than the blackest nightmare. So many people were horribly burnt and injured. It became more and more difficult to breathe …
… fire everywhere, everywhere fire, and all the time the hot wind of the firestorm threw people back into the burning houses they were trying to escape from.”
— Lothar Metzger, survivor.