Commodore Farragut's squadron and Captain Porter's mortar fleet entering the Mississippi River / sketched by an Officer of the "Mississippi".

In the early years of the war many civilian ships were confiscated for military use, while both sides built new ships. The most popular ships were tinclads—mobile, small ships that actually contained no tin. These ships were former merchant ships, generally about 150 feet in length, with about two to six feet of draft, and about 200 tons. Shipbuilders would remove the deck and add an armored pilothouse as well as sheets of iron around the forward part of the casemate and the engines. Most of the tinclads had six guns: two or three twelve-pounder or twenty-four-pounder howitzers on each broadside, with two heavier guns, often thirty-two-pounder smoothbores or thirty-pounder rifles, in the bow. These ships proved faster than ironclads and, with such a shallow draft, worked well on the tributaries of the Mississippi.