<P> As an island nation , the United Kingdom was highly dependent on imported goods . Britain required more than a million tons of imported material per week in order to be able to survive and fight . In essence , the Battle of the Atlantic was a tonnage war : the Allied struggle to supply Britain and the Axis attempt to stem the flow of merchant shipping that enabled Britain to keep fighting . From 1942 onwards , the Axis also sought to prevent the build - up of Allied supplies and equipment in the British Isles in preparation for the invasion of occupied Europe . The defeat of the U-boat threat was a pre-requisite for pushing back the Axis . The outcome of the battle was a strategic victory for the Allies -- the German blockade failed -- but at great cost : 3,500 merchant ships and 175 warships were sunk in the Atlantic for the loss of 783 U-boats ( the majority being Type VII submarines ) and 47 German surface warships , including 4 battleships ( Scharnhorst , Bismarck , Gneisenau , and Tirpitz ) , 9 cruisers , 7 raiders , and 27 destroyers . Of the U-boats , 519 were sunk by British , Canadian , or other allied forces , while 175 were destroyed by American forces ; 15 were destroyed by Soviets and 73 were scuttled by their crews before the end of the war for various causes . </P>
what was germany 's main goal in the battle of the atlantic
to stem the flow of merchant shipping that enabled Britain to keep fighting