<P> Both the German Empire and the United Kingdom relied heavily on imports to feed their population and supply their war industry . Imports of foodstuffs and war material of all European belligerents came primarily from the Americas and had to be shipped across the Atlantic Ocean , thus Britain and Germany both aimed to blockade each other . The British had the Royal Navy which was superior in numbers and could operate throughout the British Empire , while the German Kaiserliche Marine surface fleet was mainly restricted to the German Bight , and used commerce raiders and unrestricted submarine warfare to operate elsewhere . </P>
what did germany do to try to prevent goods from reaching great britain
commerce raiders unrestricted submarine warfare