Figure 10—U. S. 32-POUNDER ON BARBETTE CARRIAGE (1860).
During the Mexican War, the artillery carried 6- and 12-pounder guns, the 12-pounder mountain howitzer (a light piece of 220 pounds which had been added for the Indian campaigns), a 12-pounder field howitzer (788 pounds), the 24- and 32-pounder howitzers, and 8- and 10-inch mortars. For siege, garrison, and seacoast there were pieces of 16 types, ranging from a 1-pounder to the giant 10-inch Columbiad of 7-1/2 tons. In 1857, the United States adopted the 12-pounder Napoleon gun-howitzer, a bronze smoothbore designed by Napoleon III, and this muzzle-loader remained standard in the army until the 1880's.
The naval ironclads, which were usually armed with powerful 11- or 15-inch smoothbores, were a revolutionary development in mid-century. They were low-hulled, armored, steam vessels, with one or two revolving turrets. Although most cannonballs bounced from the armor, lack of speed made the "cheese box on a raft" vulnerable, and poor visibility through the turret slots was a serious handicap in battle.
Figure 11—U. S. NAVY 9-INCH SHELL-GUN ON MARSILLY CARRIAGE (1866).
While 20-, 30-, and 60-pounder Parrott rifles soon made an appearance in the Federal Navy, along with Dahlgren's 12- and 20-pounder rifled howitzers, the Navy relied mainly upon its "shell-guns": the 9-, 10-, 11-, and 15-inch iron smoothbores. There were also 8-inch guns of 55 and 63 "hundredweight" (the contemporary naval nomenclature), and four sizes of 32-pounders ranging from 27 to 57 hundredweight. The heavier guns took more powder and got slightly longer ranges. Many naval guns of the period are characterized by a hole in the cascabel, through which the breeching tackle was run to check recoil. The Navy also had a 13-inch mortar, mounted aboard ship on a revolving circular platform. Landing parties were equipped with 12- or 24-pounder howitzers either on boat carriages (a flat bed something like a mortar bed) or on three-wheeled "field" carriages.