iron-clads employed by the United States on the Western rivers during the late civil war were mainly river steamers, the sides above the water-line placed at an
Wrought-iron bridges. angle of about 30°, and plated with 2 to 4 inches of iron, backed with 3 feet of oak. They carried 4 to 16 guns, and some of them were made to float in 2 1/2 feet of water.
They were calculated to fight bow on, and were practically invulnerable to 100-pound shot when in this position.
The Benton, Exsex, Carondelet, Lexington, and a large number of others, were of this construction.
Toward the latter part of the war a number of monitors were built for service on the Mississippi.
A class of vessels plated with 3/4-inch iron were jocularly called tin-clads.
Their armor was a protection against rifle-balls, but was easily penetrated by shells from the lightest field-pieces.
Improvised iron-clads, consisting of river steamers plated with railroad-iron, were used by both parties on the Mississippi