The lives of civilians on both sides of the Atlantic were threatened because of the German Navy and their U boats.
The german U-boats were naval submarines used by Germany during the First World War.
They were sometimes used as fleet weapons against enemy naval warships, but their most they were most effective usage was used in an economic warfare otherwise known as commerce raiding and also to enforce a naval blockade against enemy shipping vessels.
These economic sabotage greatly affected the lives of civilians during the war.
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