Type of naval warfare in which submarines sink vessels such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules").
unrestricted submarine warfare
Germany's unrestricted submarine warfare
it was Germany.
unrestricted submarine warfare
Germany's submarine warfare was unrestricted. These attacks led to World War I.
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Help end the British blockade
Germany practiced unrestricted submarine warfare.
it referred to sinking ships
To get the blockade lifted.
Unrestricted Submarine Warfare.
American enterance into WWI.