Civil Defence

The Home Guard (initially "Local Defence Volunteers" or LDV) was a defence organisation of the British Army during the Second World War. Operational from 1940 until 1944, the Home Guard was composed of 1.5 million local volunteers otherwise ineligible for military service, such as those too young or too old to join the services, or those in reserved occupations–hence the nickname "Dad's Army". Their role was to act as a secondary defence force, in case of invasion by the forces of Nazi Germany and their allies.[1][2] They were to try to slow down the advance of the enemy, even by a few hours in order to give the regular troops time to regroup. The Home Guard continued to guard the coastal areas of the United Kingdom and other important places such as airfields, factories and explosives stores until late 1944 when they were stood down, and finally disbanded in December 1945.

https://en.wikipedia.org/wiki/Home_Guard_(United_Kingdom)

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