Smoothbore
In 1853 France introduced the Canon-obusier de 12, a 12-pounder capable of firing both shot and shell. The U.S. Army adopted the Napoleon 12-pounder in 1857 as the Model 1857 12-Pounder Napoleon Field Gun. It became the most popular field gun on both sides during the American Civil War. They were ultimately replaced by rifled barrel cannons beginning after the Civil War.