7. U-boat (submarine)
U-boat — generalized abbreviation of the German submarines that were in service with the German Navy.
Germany did not have strong enough navy that could resist the allied troops in the sea, above all, Germany hoped for its submarines, main aim of which was the destruction of trade convoys transporting goods from Canada, the British Empire and the United States to the Soviet Union and its allies in the Mediterranean. German submarines proved being incredibly effective. Later on Winston Churchill said that the only thing that scared him during the Second World War was the submarine threat. Also See: The 10 Most evil medical experiments in history of the world – #10 will leave you in the biggest shock of your life!
Studies have shown that the allies spent $ 26.4 billion to fight against German submarines. Unlike the Allied countries, Germany spent $ 2.86 billion for its U-boats. From a purely economic point of view the campaign should be considered as a success of the Germans, which makes German submarines one of the most powerful weapons of war. See the 10 Weird Military Cars of World War I.