James B. Eads, salvage king of the Mississippi River, promised President Abraham Lincoln he could build iron-armored gunboats in 65 days. On Aug. 7, 1861, Eads won a contract to build seven burly gunboats from a novel design. At $89,000 apiece, each was to carry 13 heavy cannons, have 2.5-inches of armor and be delivered to Cairo, Ill., in 60 days. The gunboats were built in the Eads Boatyard in Carondelet. The gunboat’s five boilers, seen here, sat side-by-side and powered the engines that turned a single enclosed paddlewheel. (U.S. Naval Historical Center)