The Rodman gun is any of a series of American Civil War–era columbiads designed by Union artilleryman Thomas Jackson Rodman[1] (1815–1871). The guns were designed to fire both shot and shell. These heavy guns were intended to be mounted in seacoast fortifications. They were built in 8-inch, 10-inch, 13-inch, 15-inch, and 20-inch bore (20, 25, 33, 38, and 51 cm). Other than size, the guns were all nearly identical in design, with a curving bottle shape, large flat cascabels with ratchets or sockets for the elevating mechanism. Rodman guns were true guns that did not have a howitzer-like powder chamber, as did many earlier columbiads. Rodman guns differed from all previous artillery because they were hollow cast, a new technology that Rodman developed that resulted in cast-iron guns that were much stronger than their predecessors.