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 Abraham 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.