Submarines, the Enemy Unseen
Derek Lawrence charts the origins of submarine design.
Having successfully detonated an explosive charge under water, David Bushnell of Connecticut tried to invent the means by which he could get it under a ship at sea without detection. That was in 1775. His audacious design failed, thwarted by ill-luck and uncontrolled circumstances, rather than by any technical limitation on Bushnell’s part.
There was nothing new in trying to attack warships with explosives; the novelty lay in the means. Bushnell had anticipated submarine warfare at a time when no navy in the world was ready to take it seriously.