By engaging in Guerre de Course (merchant warfare) instead of the traditional Guerre de Escadre (Fleet to Fleet sea battles).
Because the German navy was not a strong navy, they had to rely on submarines to attack merchant ships...Guerre de Course (Commerce Raiding).
Atlantic.
Submarines, commerce raiding.
It sounds as if you are looking for submarines.
Weak naval powers, such as Germany during both world wars, had to revert to "Commerce Raiding" (Guerre de Course) as they did not have a powerful enough surface navy to challenge their enemies on the high seas. Thus their submarines fought primarily merchant warfare; and not fleet actions (Guerre de Escadre).
Allied naval blockade of German ports were causing hardship to German citizens and hampering Germany's war effort. However, from the various naval battles with the Royal Navy, the Imperial German Navy had learned that it can not defeat the Allied on surface battle. Hence the aims of lifting Allied naval blockade on German ports and crippling the shipping bloodline of British Empire can not be achieved without the use of submarines. However, normal submarine warfare where U-boats have to surface and reveal its presence before searching and attacking is deemed to be too cumbersome, hence the use of unrestricted submarine warfare.
1. Germany=Submarines 2. Japan=Aircraft Carriers Germany pursued a naval war of "Guerre de Course" (Commerce raiding) Japan pursued a naval war of "Guerre de Escadre" (Fleet warfare)
Janet Marilyn Manson has written: 'Unrestricted submarine warfare, the change in U.S. policy, and German-American relations, 1939-1941' -- subject(s): Foreign relations, German Naval operations, Naval operations, German, World War, 1939-1945
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").
Colin Mayers has written: 'Submarines, admirals and navies' -- subject(s): Naval History, Naval art and science, Naval operations, Submarine, Submarine warfare, World War, 1939-1945
sucking balls
They had difficulty in combating merchant convoys to and from their overseas allied nations, as German submarines were a huge threat. Their main tactic was the use of depth-charges, which even if they did not hit the submarine directly, created an overpressure effect which could rupture a sub's hull. They also relied heavily upon heavily-armed naval escorts which had the capacity to fire ship-borne torpedoes, as well as upon their own submarines to track and hunt down German and Japanese ones.