French weapons in the American Civil War French weapons in the American Civil War had a key role in the conflict and encompassed most of the sectors of weaponry of the American Civil War ( 1861 – 1865 ) , from artillery to firearms , submarines and ironclad warships . The effect of French weapons was especially significant in field artillery and infantry . These weapons were either American productions based on French designs , or sometimes directly imported from France . Field Artillery . The " canon obusier de 12 " , introduced in the French Army in 1853 , an early type of " canon obusier " , or gun howitzer developed during the reign of Napoleon III , was the primary cannon used in the American Civil War , under the name of " 12 - pounder Napoleon Model 1857 " . Over 1 , 100 such Napoleons were manufactured by the North , and 600 by the South . The twelve - pound cannon " Napoleon " was the most popular smoothbore cannon used during the war . It was widely admired because of its safety , reliability , and killing power , especially at close range . It did not reach America until 1857 . It was the last cast bronze gun used by an American army . The Federal version of the Napoleon can be recognized by the flared front end of the barrel , called the muzzle swell . Confederate Napoleons were produced in at least six variations , most of which had straight muzzles , but at least eight cataloged survivors of 133 identified have muzzle swells . Additionally , four iron Confederate Napoleons produced by Tredegar Iron Works in Richmond , Virginia have been identified , of an estimated 125 cast . Firearms . The Minié rifle as well as the ammunition going with it , the Minié ball , developed by the French Army captain Claude - Étienne Minié , was the most widely used firearms system of the American Civil War . The Minié system was also used extensively by various manufacturers , such as Springfield , so that Springfield Model 1861 became most widely used rifle of the American Civil War . The Minié ball produced terrible wounds on those struck in battle . The large - caliber rounds easily shattered bones , and in many cases the attending surgeon simply amputate d the limb rather than risk a typically fatal secondary infection . The American Civil War , which often had many thousands of infantrymen armed with this type of ammunition , resulted in mass casualties on a scale which was inconceivable to contemporary strategists . Submarines . During the American Civil War , the Union - built and French - designed submarine " Alligator " was the first U . S . Navy submarine and the first to feature compressed air ( for air supply ) and an air filtration system . Initially hand - powered by oars , it was converted after 6 months to a screw propeller powered by a hand crank . With a crew of 20 , it was larger than Confederate submarines . " Alligator " was 47 feet ( 14 . 3 m ) long and about 4 feet ( 1 . 2 m ) in diameter . The submarine was lost in a storm off Cape Hatteras on April 1 , 1863 with no crew and under tow to its first combat deployment at Charleston . Ironclads . As the Confederacy struggled against the North , it attempted to purchase one of the latest ironclads from France , the " Stonewall " ( later to be acquired by Japan after the end of the war ) . The ship , built in Bordeaux , France by the L ' Arman shipyard in 1864 , was an ironclad ram warship . However , the French government embargoed the sale of the ship to the Confederacy in February 1864 ( prior to her launch in June 1864 ) , and then sold the ship to the Royal Danish Navy as the Stærkodder . However , L ' Arman and the Danish Navy could not agree on a price for the ship , and sometime shortly after January 7 , 1865 the vessel took on a Confederate crew and was commissioned the CSS " Stonewall " while still at sea ; L ' Arman had secretly resold her to the Confederacy . The arrival of the " formidable " " Stonewall " in America was dreaded by the Union , and several ships tried to intercept her , among them the USS " Kearsarge " and the USS " Sacramento " . In February and March , the USS " Niagara " and the " Sacramento " laid up at Ferrol , Spain , to prevent " Stonewall " from departing , but the much more powerful Confederate ship was able to make good her escape . After an eventful crossing of the Atlantic Ocean , she eventually arrived in North American waters near the end of the American Civil War , too late to have a significant effect . ( By the time of her October 1864 commissioning the Confederacy was in disarray and near defeat , its navy disintegrating , along with most other Confederate institutions . ) To avoid surrendering the vessel , Captain Page sailed her into Havana harbor and turned her over to the Captain General of Cuba for the sum of $ 16 , 000 . The vessel was then turned over to United States authorities in return for reimbursement of the same amount . She was temporarily de - commissioned , stationed at a US Navy dock , until she was offered for sale to the Japanese government of the Tokugawa shogunate .