The introduction of fast torpedo boats in the late 19th century was a serious concern to the era's naval strategists. In response, navies operating large ships introduced smaller ships to counter torpedo boats, mounting light quick-firing guns. These ships, which came to be called "torpedo boat destroyers" and later simply "destroyers", became larger and took on more roles, making torpedo attacks as well as defending against them, and eventually defending against submarines and aircraft. The destroyer eventually became the predominant type of surface warship in the guided missile age.
In the modern era, the old concept of a very small, fast, and cheap surface combatant with powerful offensive weapons is taken up by the "fast attack craft".
The American Civil War saw a number of innovations in naval warfare, including an early type of torpedo boat, armed with spar torpedoes. In 1861 President Lincoln instituted a naval blockade of Southern ports, which crippled the South's efforts to obtain war materiel from abroad. The South also lacked the means to construct a naval fleet capable of taking on the Union Navy on even terms. One strategy to counter the blockade saw the development of torpedo boats, small fast boats designed to attack the larger capital ships of the blockading fleet as a form of asymmetrical warfare.
The David class of torpedo boats were steam powered with a partially enclosed hull. They were not true submarines but were semi-submersible; when ballasted, only the smokestack and few inches of the hull were above the water line. CSS Midge was David-class torpedo boats. CSS Squib and CSS Scorpion represented another class of torpedo boats that were also low built but had open decks and lacked the ballasting tanks found on the Davids.
The Confederate torpedo boats were armed with spar torpedoes. This was a charge of powder in a waterproof case, mounted to the bow of the torpedo boat below the water line on a long spar. The torpedo boat attacked by ramming her intended target, which stuck the torpedo to the target ship by means of a barb on the front of the torpedo. The torpedo boat would back away to a safe distance and detonate the torpedo, usually by means of a long cord attached to a trigger.