The Blitz was one of the gravest threats the UK has faced in its long history. From August 1940 to May 1941, the island nation was subjected to a relentless campaign of aerial bombing. German night raids gutted towns and cities, rendering thousands homeless (250,000 Londoners were homeless by October 1940 alone), killing 43,500 civilians and wounding 139,000 more.
That the Blitz did not bring the UK to its knees is due, in large part, to a vast response by Civil Defence services and the British people themselves. Preparations for enduring a strategic bombing campaign began in the mid-1930s with the development of the Air Raid Precautions (ARP) organisation, and by late 1938 more than 700,000 people were serving in ARP roles. During the war itself, some 1.5 million people took up duties in the Civil Defence (General) services, in roles ranging from air raid wardens to ambulance drivers to heavy rescue parties.
