The Globe At War
Prior to the 20th Century, the submarine's promise as a weapons
system had been stymied by a lack of appropriate technological
solutions to the problem posed by creating a true under water
weapon. Nevertheless, experimenting during the 19th century, most
notably during the American Civil War, regarding how to solve the key
problems of powering, navigating with and fighting from an underwater
craft led to important breakthroughs. In particular, American John
Holland, born in Ireland he immigrated to America in 1873, led the
way.

Holland had realized the same engine for use on the surface did not
need to be used for underwater thrust. Therefore, Holland combined a
gasoline-powered engine, later diesel, for surface propulsion and an
electric motor for underwater use, charged by the surface engine.
Basic submarines went through little alteration over the next half
century. Holland's work meant that by the early 20th Century the
submarine had become a far more effective underwater weapon. By
the onset of the Second World War the submarine offered powerful
asymmetric capabilities to nations seeking to challenge the world's
most powerful military establishments.


Picture Courtesy US National Archives, local identifier no. 19-N-13657

German U-boat at Sea