Rephrase this sentence into your own words: "There were many types of cannons used in the the civil war, including the 6-pounder Gun, M1857 12-pounder "Napoleon", 12-pounder Howitzer, 24-pounder Howitzer, 10-pounder Parrott rifle, 3-inch Ordnance Rifle, and the 20-pounder Parrott rifle. One of the more important technological advances at the time of the Civil War was the ability mass produce rifled barrel field artillery, increasing their accuracy and range. Smoothbore cannon were still used, falling into two categories, guns and howitzers, for firing at higher trajectories and shorter ranges. "