In the 19th century many submarines were designed, from Fulton's Nautilus for Napoleon, to Holland VI in 1897, forerunner of the subs of the World Wars. Subs were designed or built for 13+ nations. A submarine-qualified Navy Captain (ret.) with years experience at the Naval War College reviews the progression of 19th century sub design, as empowered by improving technology, and the background strategic requirements driving the projects.