Electric boat) submarines designed during the second world war These submarines were the first submarines designed to operate primarily submerged, rather than spending most of their time on the surface and only submerging for brief. On may 4, 1945 one of the most advanced submarines in the world crept up to a british royal navy cruiser
The type xxi were revolutionary submarines, concentrating many innovations to revert the battle of the pacific Their package of technologies made a great leap forward in submarine design, imitated by all navies in the cold war, until the advent of nuclear power.
