Iowa-class
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U.S. Iowa-class battleships were the last class of battleship to serve in combat. When they entered service late in the Second World War, a few naval theorists suggest the exceptionally fast US Iowa-class battleships of World War II were really battlecruisers. Indeed, they were faster than the previous true South Dakota-class battleships and the planned Montana-class giants, but they had excellent armor.
Original design
They had a main battery of three triple turrets with 16"/50 caliber guns, and, for the time, advanced fire control radar: it could be used to fight targets beyond visual range. The secondary battery consisted of 20 5"-38 caliber gun guns in dual mounts.
Eventually, 20 quad mounted 40mm-56 caliber guns, 29 20mm single mounted autocannon, and several .50 caliber M2 machine guns were added to thicken antiaircraft defense, requiring an additional 1,900 crew members. These were obsolete, however, by the end of the Second World War. While the 5" guns were retained for shore bombardment, the Iowas depended on other, more specialized missile-armed vessels for air defense.
Comparative effectiveness
While their main guns were 16" rather than the 18.1" of the largest Japanese Yamato-class battleships, their speed, fire control, and probably better-penetrating ammunition might well have led them to defeat Yamato and Musashi, if the aviators had not sunk them first.